Integrated Mid Term Exam Review 2011-2012

Mixing together salt and water is an example of a physical change. This is because when salt is added to water, it dissolves and forms a homogeneous mixture. Although the salt molecules disperse throughout the water, no new substances are formed, and the chemical composition of both salt and water remains unchanged. Therefore, this process does not involve any chemical reactions and is considered a physical change.

Y is the container with the least dense liquid because density is a measure of how much mass is packed into a given volume. The liquid in container Y has the least mass compared to its volume, making it less dense than the liquids in containers X, W, and Z.

Aluminum (Al) is a pure substance. It is a chemical element with a specific atomic number and atomic mass. Pure substances are made up of only one type of atom or molecule, and they cannot be separated into simpler substances by physical means. In the case of aluminum, it consists of only aluminum atoms, making it a pure substance.

An isotope is when an atom has the same number of protons but a different number of neutrons, not electrons. The number of protons in an atom determines its atomic number and the number of electrons determines its overall charge. Isotopes have the same atomic number but different mass numbers due to the varying number of neutrons.

Alkali metals are highly reactive with water and have only 1 valence electron. This means that they readily lose this electron to form a positive ion when they come into contact with water. This reaction with water produces hydrogen gas and a strong alkaline solution. The reactivity of alkali metals increases as you move down the group in the periodic table, with lithium being the least reactive and francium being the most reactive.

Atoms go through ionization in order to get a full outer shell of electrons. Ionization occurs when an atom gains or loses electrons, resulting in the formation of ions. This process allows the atom to achieve a stable electron configuration, similar to the nearest noble gas, by either gaining or losing electrons. Therefore, the statement is true.

When an atom loses an electron, it becomes positively charged because it now has more protons than electrons. This positively charged atom is called a cation.

Alkaline Earth Metals are a family of elements found in the earth's crust. These elements have a tendency to lose two electrons during ionization, resulting in a charge of +2. Therefore, Alkaline Earth Metals are the correct answer for this question.

When an atom loses or gains an electron, it undergoes ionization. Ionization is the process in which an atom becomes an ion by either losing or gaining electrons. This process can result in the formation of a positively charged ion (cation) if the atom loses electrons, or a negatively charged ion (anion) if the atom gains electrons. Ionization plays a crucial role in various chemical reactions and is important in understanding the behavior of ions in solutions and in the formation of compounds.

Electrons are subatomic particles that have a negative charge. They orbit around the nucleus of an atom and are involved in chemical reactions and the flow of electricity. Protons, on the other hand, have a positive charge, while neutrons have no charge. Therefore, the correct answer is electron.

A proton is a subatomic particle found in the nucleus of an atom. It carries a positive charge, which is equal in magnitude but opposite in sign to the charge of an electron. This positive charge is what allows protons to interact with electrons and other particles, playing a crucial role in the structure and behavior of matter.

A neutron has a charge of neutral. This means that it does not have a positive or negative charge. Neutrons are subatomic particles found in the nucleus of an atom along with protons. While protons have a positive charge and electrons have a negative charge, neutrons have no charge. They are essential for the stability of an atom and contribute to its mass.

Neutrons and protons are located in the nucleus of an atom. Neutrons have no charge and protons have a positive charge. Electrons, on the other hand, are located outside the nucleus in energy levels or orbitals. Megatrons are not subatomic particles and do not exist.

Dalton's atomic theory was accepted more than Democritus's theory because Dalton's model had evidence to support it. Unlike Democritus, Dalton conducted numerous experiments and gathered empirical data to support his theory. This evidence-based approach made Dalton's theory more convincing and credible to the scientific community. Additionally, people were ready for change and open to new ideas during Dalton's time, which further contributed to the acceptance of his atomic theory.

The element belongs to the Halogens family because it is the only option that includes elements from that group. Halogens are a group of highly reactive nonmetals that include elements such as fluorine, chlorine, bromine, iodine, and astatine. They are known for their tendency to gain one electron to achieve a full outer shell, making them highly reactive and capable of forming compounds with other elements.

The given question is asking about the type of bond. The correct answer is "covalent". Covalent bonds occur when two atoms share electrons. In this type of bond, the electrons are not transferred from one atom to another, but rather are shared between the atoms. Covalent bonds are typically formed between nonmetals.

Fluorine has the highest electron affinity among the given elements. Electron affinity is the amount of energy released when an electron is added to a neutral atom to form a negative ion. Fluorine has a high electron affinity because it has a small atomic radius and a high effective nuclear charge, which means it can attract and hold on to an additional electron more strongly than the other elements listed.

Using a crushed tablet in warm water would result in the fastest dissolution of Alka Seltzer. Crushing the tablet increases its surface area, allowing for more contact between the tablet and the water. Warm water increases the kinetic energy of the water molecules, causing them to move faster and collide more frequently with the tablet particles. This increased collision rate leads to a faster dissolution of the tablet and therefore a quicker release of the medicine into the body.

The answer is surface area because a substance broken down into smaller chips would have a greater surface area making the reaction happen faster

Al 1,2 Al 2
O 7,10,18 O 13,16,18
H 8,12 H 2,8,12
S 1,3 S 3

The correct answer is exothermic. When water is added to the heater in Army MRE's, a chemical reaction occurs that releases heat. This heat is transferred to the food, making it hot and delicious. An exothermic reaction is characterized by the release of heat energy to the surroundings.

C 3 C 1,3
H 8 H 8
O 2,10 O 10

The given chemical equation is unbalanced. To balance it, we need to ensure that the number of atoms of each element is the same on both sides of the equation. We can start by balancing the hydrogen atoms. Since there are 2 hydrogen atoms on the left side and 2 hydrogen atoms on the right side, we can assign a coefficient of 2 to H2. Next, we can balance the oxygen atoms. There are 2 oxygen atoms on the left side and 2 oxygen atoms on the right side, so we can assign a coefficient of 1 to O2. Finally, we can balance the equation by assigning a coefficient of 2 to H2O, resulting in the balanced equation: 2H2 + O2 => 2H2O. Therefore, the coefficients are 2, 1, 2.

In a chemical change, bonds between atoms are broken and atoms are rearranged to form new substances. This is different from a physical change where no new atoms are formed and atoms are not lost. In a physical change, bonds may be broken, but they are not rearranged to form new substances. Therefore, the correct answer is that in a chemical change, bonds are broken and atoms are rearranged.

A chemical reaction occurs when bonds between atoms are broken and rearranged to form new chemicals. This process involves a change in the chemical composition and properties of the substances involved. In contrast, a physical change refers to a change in the physical state or appearance of a substance without any alteration in its chemical composition. The Law of Proportions is a principle that states that chemical compounds always contain the same proportion of elements by mass. Chemical property refers to the characteristic behavior of a substance in a chemical reaction.

The application of science to meet human needs refers to using scientific knowledge and principles to develop practical solutions, tools, and techniques. This is commonly known as technology. Technology involves the creation, modification, and utilization of various artifacts, systems, and processes to fulfill human needs and improve the quality of life. It encompasses a wide range of fields and industries, including electronics, engineering, medicine, communication, transportation, and more.

A scientific law is a statement that describes a natural event or phenomenon, based on repeated observations and experiments. It summarizes the behavior or pattern observed in nature, without providing an explanation for why it occurs. Laws are often expressed in mathematical equations or formulas and are widely accepted as true within a certain range of conditions. They serve as a foundation for scientific understanding and can be used to make predictions about future events.

Scientists use models to represent real situations and to make predictions. Models are simplified representations of complex systems or phenomena that help scientists understand and analyze them. By using models, scientists can simulate different scenarios and predict how the real situation might behave under different conditions. This allows them to make informed decisions and draw conclusions about the real world based on their predictions from the models.

The statement is true because using mathematics to describe a scientific event involves creating a model. A model is a simplified representation of a real-world phenomenon that allows scientists to make predictions and understand the underlying principles. By using mathematical equations and formulas, scientists can quantify and analyze the variables and relationships involved in a scientific event, leading to a better understanding of the event and its outcomes.

A scientific model is a representation of a real event or object that is usually too large or small to see. It is used to study and understand complex phenomena by simplifying them and making them easier to visualize and manipulate. Scientific models can be physical, such as a scaled-down replica of a building, or conceptual, such as a mathematical equation that describes the behavior of a system. They are widely used in various scientific disciplines, including physics, chemistry, biology, and engineering, to test hypotheses, predict outcomes, and communicate ideas.

A bar graph would be the best kind of graph to show the density of different substances because it allows for easy comparison between the densities of each substance. Each substance can be represented by a separate bar, with the height of the bar indicating the density. This visual representation allows for a clear understanding of the relative densities of the substances being compared.

The speed of light, which is 3.0 X 10^8 m/s, can be expressed in standard notation as 300,000,000 m/s.

The given number, .0009234, is a very small number. In scientific notation, a number is written in the form of a decimal between 1 and 10, multiplied by a power of 10. To convert .0009234 to scientific notation, we move the decimal point 4 places to the right to get 9.234. Since we moved the decimal point to the right, the exponent of 10 is negative. Therefore, the number .0009234 would be written in scientific notation as 9.2 X 10^-4.

The number .000670 has three significant figures because all non-zero digits are significant and any zeros between non-zero digits are also significant.

The increase in ridership between 1998 and 2008 was 100,000.

The most likely reason for the increase in ridership and decrease in casualties in NYC from 1998-2008 is that NYC made bicycle lanes on most downtown roads. By creating dedicated lanes for bicycles, it provided a safer and more accessible environment for cyclists, encouraging more people to ride bikes. This increase in the number of people riding bikes would naturally lead to an increase in ridership and a decrease in casualties as the infrastructure became more accommodating to cyclists.

The correct answer is 0.44 Kg per KM. This means that a single driver in a large 4WD vehicle emits 0.44 kilograms of greenhouse gases for every kilometer driven.

A person with apnea sleep takes more total breaths per minute because apnea is a sleep disorder characterized by pauses in breathing or shallow breaths during sleep. These pauses can occur multiple times throughout the night, causing the person to take more breaths per minute in order to compensate for the interrupted breathing.

During sublimation, a substance transitions directly from a solid to a gas without going through the liquid phase. This process requires energy input to break the intermolecular forces holding the solid together and to overcome the attractive forces between the gas molecules. Therefore, energy is gained during sublimation.

When a substance goes from a solid to a liquid, it is called melting. This process occurs when the substance is heated and its particles gain enough energy to break free from their fixed positions in the solid lattice and move more freely, resulting in a change in state from solid to liquid.

The correct answer is pure substance. Capsaicin is a specific compound with a chemical formula of C18H27NO3, which means it is a pure substance. Pure substances have a fixed composition and cannot be separated into other substances by physical means. In this case, capsaicin is a pure substance because it consists of only one type of molecule, which is capsaicin itself.

When multiple pure substances are added together, it is called a mixture. A mixture refers to a combination of two or more substances that are not chemically bonded and can be separated by physical means. In a mixture, the substances retain their individual properties and can exist in varying proportions. This is different from a compound, which is formed when two or more elements chemically combine to create a new substance with different properties. An element is a pure substance that cannot be broken down into simpler substances, and a molecule refers to a group of atoms bonded together.

Blood is considered a homogeneous mixture because it is composed of multiple components, such as red and white blood cells, plasma, and platelets, that are uniformly distributed throughout. These components cannot be easily separated or distinguished by the naked eye, making blood appear the same throughout its composition.

The image shows six molecules.

O2 is a molecule because it consists of two oxygen atoms bonded together. Molecules are formed when two or more atoms chemically combine, and in the case of O2, two oxygen atoms come together to form a stable molecule.

All compounds are indeed molecules. A molecule is a group of atoms bonded together, and a compound is a type of molecule that consists of two or more different elements. Therefore, every compound is a molecule, but not every molecule is a compound.

There are 92 naturally occurring elements found on Earth. These elements are the building blocks of matter and cannot be broken down into simpler substances. They range from hydrogen, the lightest element, to uranium, the heaviest naturally occurring element. These elements are found in various forms and combinations, and they play a crucial role in the composition of everything around us, including the air we breathe, the water we drink, and the materials that make up our planet.

Cooking an egg involves a chemical change. When heat is applied to the egg, the proteins in the egg denature and coagulate, resulting in the solidification of the egg white and yolk. This process cannot be reversed, as the chemical composition of the egg undergoes a permanent change. Therefore, cooking an egg is an example of a chemical change rather than a physical change, which refers to changes that do not alter the chemical composition of a substance.

Section 3 represents water in the liquid form only because it is the section that is labeled as "liquid" and does not have any other states of matter mentioned. This implies that in section 3, water is present only in its liquid state and not as a solid or gas.

The average atomic mass of an element is calculated by taking into account the mass of each isotope and its relative abundance. In this case, the given answer of 21.087 is the calculated average atomic mass of the three isotopes of Neon. It is likely that the mass and relative abundance of each isotope were provided, and by using these values in the calculation, the average atomic mass was determined to be 21.087.

Noble gases have a full outer shell of electrons, making them stable and unreactive with other elements. This is due to their complete valence electron configuration, which satisfies the octet rule. Therefore, noble gases do not readily form chemical bonds or react with other elements, making them highly inert.

False. An atom of Helium has a full outer shell of 2 electrons, not 8. The first energy level can hold a maximum of 2 electrons, and Helium only has 2 electrons in total. Therefore, its outer shell is already full.

Radon is a chemical element with atomic number 86. The atomic number represents the number of protons in an atom, which is also equal to the number of electrons in a neutral atom. Therefore, there are 86 electrons in 1 element of Radon.

When an atom gains an electron, it becomes negatively charged because the number of electrons exceeds the number of protons. This negatively charged atom is called an anion.

The Periodic Law is a fundamental principle in chemistry that states that the properties of elements are periodic functions of their atomic numbers. This means that as the number of protons in the nucleus increases, the chemical and physical properties of the elements also exhibit a periodic pattern. This pattern is observed in the periodic table, where elements are arranged in order of increasing atomic number. Therefore, the statement that the Periodic Law states that when atoms are arranged by the number of protons they show a pattern of chemical and physical properties is true.

Sodium has higher metallic properties compared to chlorine. Metallic properties refer to the ability of an element to conduct heat and electricity, as well as its malleability and ductility. Sodium is a metal, while chlorine is a non-metal. Metals generally have higher metallic properties due to their ability to easily lose electrons and form positive ions. Sodium readily loses its outermost electron to form a stable positive ion, making it a good conductor of heat and electricity. Chlorine, on the other hand, tends to gain electrons to form stable negative ions, which limits its metallic properties.

The electron is by far the smallest particle among the given options. Protons and neutrons are both found in the nucleus of an atom and are much larger in size compared to the electron, which orbits around the nucleus. Electrons have a negligible mass and are considered to be point-like particles, meaning they have no size or structure. Their small size and negligible mass make them significantly smaller than protons and neutrons.

Bohr's Model is the correct answer because it is based on the idea that electrons orbit the nucleus in fixed energy levels, similar to how planets orbit the sun. This model was proposed by Niels Bohr in 1913 and it successfully explained the stability of atoms and the emission and absorption of light. According to Bohr's Model, electrons occupy specific orbits or energy levels, and they can jump between these levels by absorbing or emitting energy. This model was a significant advancement in our understanding of atomic structure.

The S orbitals can hold a maximum of 2 electrons. This is because the S orbital is the first energy level and has only one sublevel, which can hold a maximum of 2 electrons according to the Pauli exclusion principle.

The atomic number of an element represents the number of protons in the nucleus of an atom. Protons carry a positive charge and are responsible for determining the element's identity. The number of protons also determines the element's position on the periodic table. Therefore, the atomic number provides information about the element's identity and its placement in the periodic table.

A covalent bond is formed when two atoms share electrons. In this type of bond, the electrons are shared between the atoms rather than being transferred completely from one atom to another. This sharing of electrons allows both atoms to achieve a more stable electron configuration. Covalent bonds typically occur between nonmetal atoms.

Atoms join to form bonds in order to achieve a full outer shell of valence electrons. This is because atoms are more stable when their outermost energy level is complete. By sharing, gaining, or losing electrons through bonding, atoms can achieve a full outer shell and become more stable.

Alkali metals have one valence electron. This is because alkali metals belong to Group 1 of the periodic table, which means they have one electron in their outermost energy level or valence shell. Having only one valence electron makes alkali metals highly reactive and eager to lose that electron to achieve a stable electron configuration. This is why alkali metals are known for their strong tendency to form positive ions.

The given answer, metallic, suggests that the bond shown in the picture is a metallic bond. Metallic bonding occurs between metal atoms, where the valence electrons are free to move throughout the structure, creating a "sea" of delocalized electrons. This type of bonding is typically found in metals and results in properties such as high electrical and thermal conductivity, malleability, and ductility.

Polyatomic ions can bond to each other because they are charged particles that contain multiple atoms. These ions have either a positive or negative charge and can form ionic bonds with other ions of opposite charge. The attraction between the positive and negative charges allows the polyatomic ions to bond together and form compounds.

Cl is the anion because it is a negatively charged ion that is formed when chlorine gains an electron. In this question, Na and Cl are the elements sodium and chlorine, respectively. Na is a cation because it is a positively charged ion that is formed when sodium loses an electron. Therefore, the correct answer is Cl.

NaCl has a higher melting point compared to CO2 because it is an ionic compound composed of positively charged sodium ions and negatively charged chloride ions. These ions are held together by strong electrostatic forces, resulting in a high melting point. On the other hand, CO2 is a covalent compound with weak intermolecular forces between its molecules, leading to a lower melting point.

It is colder than the other two because the reaction is happening at a slower rate

you must DECREASE the pressure in order to increase the reaction rate. This is because decreasing the pressure will allow for the particles to move faster and contact each other more often

The experiment described in the question is said to have a magical reaction happening at the 20 second mark. Since the question does not provide any specific details about the nature of this reaction, we can only infer from the given answer choices. Endothermic reactions are characterized by absorbing heat or energy from their surroundings, while exothermic reactions release heat or energy. Since the question does not mention any release of heat or energy, we can assume that the magical reaction at the 20 second mark is an endothermic reaction.

The number 4.065 has four significant figures because all of the digits in the number are non-zero and are therefore considered significant.

False. The particles in a solid do not stop moving completely. While the particles in a solid are tightly packed and have limited mobility compared to those in a liquid or gas, they still vibrate in their fixed positions. This vibration is due to the thermal energy possessed by the particles. Therefore, even in a solid state, the particles are constantly in motion, although their movement is restricted.

Changing the amount of energy or pressure can affect the states of matter because these factors can cause the particles in a substance to move faster or slower. Increasing the energy or pressure can cause the particles to move more rapidly, leading to a change in state from solid to liquid or from liquid to gas. Conversely, decreasing the energy or pressure can cause the particles to slow down and move closer together, resulting in a change in state from gas to liquid or from liquid to solid. Therefore, it is true that changing the amount of energy or pressure can affect the states of matter.

The correct answer is elements and compounds. Elements are substances made up of only one type of atom, while compounds are substances made up of two or more different types of atoms chemically bonded together. This means that both elements and compounds are pure substances because they have a fixed composition and properties that are distinct from other substances. Atoms and molecules are not the only two types of pure substances because atoms can exist as elements or combine to form molecules, and molecules can exist as compounds or mixtures. Heterogeneous and homogeneous are not types of pure substances, but rather describe the composition of mixtures.

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The symbol "O2" represents a diatomic molecule of oxygen, which is not considered a compound. A compound is a substance formed by the chemical combination of two or more elements in definite proportions. In the case of O2, it is made up of two oxygen atoms bonded together, but it is still considered an element rather than a compound.

Halogens are a family of elements that often form anions and are highly reactive with alkali metals. This is because halogens have seven valence electrons and need one more electron to achieve a full outer shell. They readily gain an electron from alkali metals to form stable compounds. Therefore, halogens fit the description given in the question. Transition metals, alkali metals, and noble gases do not exhibit the same characteristics as halogens.

The atomic number of an element represents the number of protons in its nucleus. Since the element given is Radon, which has an atomic number of 86, it means that it has 86 protons. The atomic mass of an element represents the sum of the protons and neutrons in its nucleus. The atomic mass of Radon is 222. Therefore, to find the number of neutrons, we subtract the atomic number from the atomic mass: 222 - 86 = 136. Thus, there are 136 neutrons in one element of Radon.

Radon has a lower ionization energy compared to Neon. Ionization energy refers to the energy required to remove an electron from an atom or ion in the gaseous state. Radon, being a larger atom with more electron shielding and a higher number of electron shells, experiences a weaker attraction between the nucleus and the outermost electrons. This results in a lower ionization energy for Radon compared to Neon, which is a smaller atom with stronger nuclear attraction.

The bottom left corner of the periodic table refers to the elements in the s-block and the f-block. These elements have the highest atomic radius because they have the highest number of energy levels and the least amount of effective nuclear charge. As we move down a group, the number of energy levels increases, resulting in a larger atomic radius. Additionally, the f-block elements, also known as the lanthanides and actinides, have an additional set of electrons in their f-orbitals, which further increases their atomic radius.

Dalton's atomic model, proposed in the early 19th century, described atoms as indivisible and indestructible particles. According to Dalton, atoms were the smallest units of matter and did not contain any subatomic particles such as protons, neutrons, or electrons. Therefore, the given image, which accurately depicts subatomic particles, does not align with Dalton's atomic model.

An ionic bond is formed when there is a strong attraction between oppositely charged ions. In this type of bond, one atom donates electrons to another atom, resulting in the formation of positively and negatively charged ions. These ions are held together by electrostatic forces, creating a stable bond. Ionic bonds typically occur between a metal and a non-metal, where the metal atom loses electrons to become a positively charged ion, and the non-metal atom gains those electrons to become a negatively charged ion. This bond is characterized by high melting and boiling points, as well as the ability to conduct electricity when dissolved in water.

A polyatomic ion is a group of two or more atoms that are covalently bonded and act as a single ion. Unlike individual ions, polyatomic ions have a charge and can form compounds with other ions. They are often found in ionic compounds and play important roles in chemical reactions.

Ionic bonds will conduct electricity when dissolved in water because they involve the transfer of electrons from one atom to another, creating ions with positive and negative charges. These ions are able to move freely in the water, allowing for the flow of electric current. In contrast, covalent bonds involve the sharing of electrons between atoms and do not create charged ions, therefore they do not conduct electricity when dissolved in water.

At a higher concentration, the reaction rate is faster because there are more reactant molecules available to collide and react with each other. This leads to the formation of a greater amount of products in a shorter period of time.

Chemists need to work with balanced equations because of the law of conservation of mass. This law states that mass cannot be created or destroyed in a chemical reaction, only rearranged. By balancing the equation, chemists ensure that the same number of atoms of each element are present on both sides of the reaction. This allows them to accurately calculate the amounts of reactants and products involved in the reaction and understand the stoichiometry of the reaction.

John Dalton's atomic theory, developed in the early 1800s, includes the following principles: all matter is made up of atoms, atoms of each element are exactly alike, and each element has different atoms. However, the statement "atoms have subatomic particles" is not part of Dalton's atomic theory. Dalton believed that atoms were indivisible and did not have any subatomic particles. Later discoveries, such as the existence of protons, neutrons, and electrons, led to the development of the modern atomic theory.

Accuracy refers to how close a measurement is to the true or accepted value. It is a measure of how well a measurement represents the actual value being measured. A measurement can be precise, meaning it has a low level of random error, but not accurate if it is consistently off from the true value. Therefore, the extent to which a measurement approaches the true value is referred to as accurate.

The oxidation of a substance is a chemical property because it involves a chemical reaction where the substance combines with oxygen or loses electrons. This process leads to a change in the chemical composition of the substance, resulting in the formation of new compounds or the alteration of its properties. Physical properties, on the other hand, are characteristics that can be observed or measured without changing the substance's chemical composition. Since oxidation involves a chemical reaction and leads to a change in composition, it is considered a chemical property.

According to Bohr's model of the atom, the 3rd energy level can hold a maximum of 18 electrons, not 8. This is because the third energy level has three sublevels: s, p, and d, which can accommodate 2, 6, and 10 electrons respectively. Therefore, the statement that the 3rd energy level can only hold up to 8 electrons is incorrect.

A metallic bond is formed when positively charged metal ions are surrounded by a sea of delocalized electrons. In this type of bond, the positively charged nucleus of one atom is attracted to the negatively charged electron cloud of another atom, creating a strong bond between the atoms. This type of bonding is typically found in metals, where the electrons are able to move freely throughout the structure, giving metals their characteristic properties such as high electrical and thermal conductivity, malleability, and ductility.

The element in question has 35 valence electrons. The number 35 is the atomic number of bromine (Br), which is located in Group 17 of the periodic table. Elements in Group 17, also known as the halogens, have 7 valence electrons. Since bromine is in the 4th period of the periodic table, it also has 4 electron shells. Therefore, the correct answer is 35.

A measurement that is close to the true value indicates accuracy, while having several significant figures indicates precision. Therefore, a measurement that is both close to the true value and has several significant figures is likely to be both precise and accurate.

Alkali metals, such as lithium, sodium, and potassium, have one valence electron. In order to achieve a stable electron configuration, they tend to lose this electron and form a positive ion. On the other hand, non-metals, such as oxygen or chlorine, tend to gain electrons to achieve a stable electron configuration. Therefore, when alkali metals react with non-metals, they transfer their valence electron to the non-metal, resulting in the formation of positive and negative ions. This electrostatic attraction between the oppositely charged ions leads to the formation of an ionic bond. Hence, alkali metals are likely to form ionic bonds.