1.
Bila Al (nomor atomnya = 13) membentuk Al3+ maka susunan elektron terluarnya adalah …..
Correct Answer
B. B. 2s2 2P6
Explanation
The correct answer is B. 2s2 2P6. This is because when Al (atomic number = 13) forms Al3+, it loses three electrons from its outermost energy level. The electron configuration of Al is 1s2 2s2 2p6 3s2 3p1. By losing three electrons, the outermost energy level becomes 2s2 2p6, which matches the given answer.
2.
Unsur X dengan konfigurasi elektron 1s2 2s2 2p6 2s1 mempunyai sifat …
Correct Answer
D. D. dapat membentuk senyawa halida dengan klor dengan rumus XCl
Explanation
The given electron configuration indicates that element X has 1 valence electron in its 2s orbital. This suggests that element X belongs to Group 1 of the periodic table, also known as the alkali metals. Alkali metals readily form ionic compounds with halogens, such as chlorine (Cl), to form halides. Therefore, element X can form a halide compound with chlorine, represented by the formula XCl. This explanation aligns with option D.
3.
Unsur-unsur golongan alkali tanah sifat-sifat kimianya hampir sama karena
Correct Answer
C. C. jumlah elektron pada kulit terluarnya sama
Explanation
The correct answer is C because elements in the alkaline earth metal group have the same number of electrons in their outermost shell. This similarity in electron configuration leads to similar chemical properties among these elements.
4.
Diantara unsur-unsur di bawah ini yang paling mudah membentuk ion negatif adalah........
Correct Answer
A. A. 17Cl
Explanation
Chlorine (Cl) is the most likely element to form a negative ion because it is in Group 17 of the periodic table, also known as the halogens. Halogens have a tendency to gain one electron to achieve a stable electron configuration, resulting in a negative charge. Therefore, chlorine (Cl) is the element that is most likely to easily form a negative ion.
5.
Suatu unsur X dengan nomor atom 27 mempunyai jumlah orbital …
Correct Answer
E. E. 15
Explanation
The element with an atomic number of 27 is cobalt (Co). Cobalt has 27 electrons, and based on the Aufbau principle, these electrons will fill up the orbitals in increasing order of energy. The first two electrons will fill the 1s orbital, the next two will fill the 2s orbital, and the next six will fill the 2p orbital. After that, the remaining 17 electrons will fill the 3s, 3p, 3d, 4s, and 4p orbitals. Therefore, cobalt has a total of 15 orbitals.
6.
Konfigurasi elektron atom Fe [Ar] 3d6 4s2 jumlah elektron yang tidak berpasangan pada atom Fe adalah …
Correct Answer
D. D. 4
Explanation
The electron configuration of Fe is [Ar] 3d6 4s2. This means that Fe has 6 electrons in its 3d orbital and 2 electrons in its 4s orbital. In order to determine the number of unpaired electrons, we look at the electrons in the outermost energy level, which is the 4s orbital. Since there are 2 electrons in the 4s orbital and they have opposite spins, they are paired and do not contribute to the number of unpaired electrons. Therefore, the number of unpaired electrons in Fe is equal to the number of electrons in the 3d orbital, which is 6. Hence, the correct answer is D. 4.
7.
Diantara unsur-unsur 3P, 12Q, 19R, 33S dan 53T, yang terletak dalam golongan yang sama........
Correct Answer
C. C. P dan R
Explanation
The elements given in the question are 3P, 12Q, 19R, 33S, and 53T. The question asks for the elements that belong to the same group. By looking at the elements, we can see that the numbers (3, 12, 19, 33, 53) are not relevant to determining the group. The letters (P, Q, R, S, T) are what we need to focus on. Among these letters, only P and R are mentioned together (3P and 19R), indicating that they belong to the same group. Therefore, the correct answer is C. P and R.
8.
Unsur yang jari-jari atomnya terbesar adalah …
Correct Answer
A. A. 11Na
Explanation
The element with the largest atomic radius is Na (sodium) because it is located in the first group of the periodic table, which means it has the least amount of electrons in its outermost shell. As a result, the electrons are not strongly attracted to the nucleus, causing the atomic radius to be larger compared to the other elements given.
9.
Suatu logam divalent L sebanyak 8 gram, dilarutkan ke dalam HCl berlebih dan diperoleh 4,48
dm3 gas hidrogen (STP). Jika logam ini memiliki 20 netron, maka letaknya dalam sistem
periodik …
Correct Answer
C. C. golongan IIA, periode 4
Explanation
The given information states that 8 grams of a divalent metal L produces 4.48 dm3 of hydrogen gas at STP. From this information, we can calculate the molar mass of L, which is 2 grams/mol. Since the metal has 20 neutrons, we can determine that it is in the 4th period of the periodic table. Additionally, since it is divalent, it belongs to the IIA group. Therefore, the correct answer is golongan IIA, periode 4.
10.
Suatu senyawa dengan rumus molekul XY. Jika konfigurasi electron atom X: 1s2 2s2 2p6 3s2
3p6 4s2 dan konfigurasi electron atom Y: 1s2 2s2 2p4, maka XY mempunyai ikatan…
Correct Answer
E. E.Ion
Explanation
The given question provides the electron configurations of atoms X and Y. Atom X has a full outer shell with 2 electrons in the 4s orbital, indicating that it is a cation (positively charged ion). Atom Y has 4 electrons in its outer shell, which means it needs to gain 4 more electrons to achieve a full outer shell. Therefore, when atom X loses 2 electrons to atom Y, they will form an ionic bond, resulting in XY being an ion.