Question

question 7 (1 point)
(02 03 mc)
magnesium (mg) has an atomic number of 12. what is the electron configuration of magnesium?
o a 1s²1p⁶2s²2p²
o b 1s²1p⁶1d⁴
o c 1s²2s²2p⁶3s²
o d 1s²2s²2p⁶2d²
question 8 (1 point)
(02 03 mc)
the diagram shows four different locations in an atom.
which locations are likely to have subatomic particles with the least mass?
o a 1 and 2
o b 2 and 3
o c 1 and 4
o d 3 and 4

Explanation:

1. For magnesium with atomic number 12, electrons fill orbitals in the order of increasing energy following the Auf - bau principle. The first energy level (n = 1) has 1s orbital which can hold 2 electrons. The second energy level (n = 2) has 2s (holds 2 electrons) and 2p (holds 6 electrons) orbitals. The remaining 2 electrons go into the 3s orbital of the third energy level. So the electron - configuration is $1s^{2}2s^{2}2p^{6}3s^{2}$.
2. Subatomic particles with the least mass are electrons. Electrons are located in the electron - cloud outside the nucleus. In the given diagram, locations 1 and 4 represent the electron - cloud regions.

Answer:

Question 7: C. $1s^{2}2s^{2}2p^{6}3s^{2}$
Question 8: C. 1 and 4