1.
The charge of an atom is
Correct Answer
C. Neutral
Explanation
The charge of an atom is neutral because an atom contains an equal number of positively charged protons and negatively charged electrons. Protons are located in the nucleus, and electrons orbit around the nucleus. The positive charge from the protons exactly cancels out the negative charge from the electrons, resulting in a net charge of zero. When the number of protons and electrons is equal, the atom is electrically neutral. Any imbalance between protons and electrons would result in a charged particle called an ion.
2.
Most of the atom's volume (space) is
Correct Answer
C. Empty space
Explanation
Most of the volume of an atom is empty space. The nucleus, which contains protons and neutrons, is extremely small and dense compared to the overall size of the atom. Electrons occupy the regions around the nucleus in what is called the electron cloud, but this space is still mostly empty. The electrons themselves are very tiny compared to the nucleus and are spread out over a large area, meaning that the majority of an atom's volume is essentially empty space.
3.
Which element has 29 protons?
Correct Answer
D. Copper
Explanation
An element’s identity is defined by the number of protons in its nucleus, known as its atomic number. The element with 29 protons is copper (Cu), which is why its atomic number is 29. Each element on the periodic table has a unique atomic number, and no two elements have the same number of protons. Copper is a transition metal known for its high electrical and thermal conductivity, and its atomic structure—specifically having 29 protons—plays a crucial role in its chemical behavior and placement in the periodic table.
4.
An atom has 40 electrons and 46 neutrons. How many protons does it have?
Correct Answer
A. 40
Explanation
In a neutral atom, the number of protons is equal to the number of electrons to balance the charges. Since this atom has 40 electrons, it must also have 40 protons. The number of neutrons, in this case, 46, does not affect the number of protons or the overall charge but can affect the atom's mass.
5.
An atom has 22 electrons and 24 neutrons. What is the atomic number?
Correct Answer
A. 22
Explanation
The atomic number of an element is determined by the number of protons in its nucleus. Since a neutral atom has an equal number of protons and electrons, an atom with 22 electrons must have 22 protons. Thus, the atomic number is 22, which corresponds to the element titanium (Ti) on the periodic table.
6.
The atom's mass is found mostly in the
Correct Answer
A. Nucleus
Explanation
The atom's mass is found mostly in the nucleus. The nucleus is the central part of an atom that contains protons and neutrons. Protons have a positive charge and neutrons have no charge, together they make up the majority of the atom's mass. Electrons, on the other hand, are negatively charged particles that orbit around the nucleus in the electron cloud. While electrons contribute to the overall charge of the atom, they have a negligible mass compared to protons and neutrons. Therefore, the mass of an atom is primarily concentrated in the nucleus.
7.
A particle has 25 protons, 22 electrons and 24 neutrons. Which of these statement is true?
Correct Answer
B. The particle is an ion
Explanation
A particle with 25 protons and 22 electrons has an imbalance of positive and negative charges, resulting in a net positive charge (3 more protons than electrons). This makes it an ion, specifically a cation because it has a positive charge. An atom is neutral, an isotope has variations in the number of neutrons, and the nucleus is just the central part of an atom containing protons and neutrons.
8.
Two atoms of the same
element that have the same mass will have
Correct Answer
E. A & B
Explanation
Two atoms of the same element that have the same mass will have the same number of protons and the same number of electrons. The number of protons determines the atomic number and identifies the element, while the number of electrons determines the overall charge of the atom and its reactivity. Therefore, if two atoms have the same mass, it means they have the same number of protons and electrons. The number of neutrons can vary in isotopes of the same element, so it is not necessarily the same for atoms with the same mass.
9.
What is the atomic number of an atom that has 12 protons, 13 neutron and 12 electrons?
Correct Answer
B. 12
Explanation
The atomic number of an atom is determined by the number of protons in its nucleus. Since this atom has 12 protons, its atomic number is 12, which corresponds to the element magnesium (Mg). The number of neutrons (13) and electrons (12) does not affect the atomic number.
10.
What is the total number of electrons in the Na atom below?23 + Na11
Correct Answer
A. 10
Explanation
The Na atom has an atomic number of 11, which means it has 11 protons. Since atoms are neutral, it also has 11 electrons. However, the question asks for the total number of electrons in the Na atom below, which is 23. This is incorrect because it adds the atomic number of Na (11) to the atomic mass of Na (12), which is incorrect. Therefore, the correct answer is 10, which is the atomic number of Na.