Question

1. the element with electron configuration $1s^2 2s^2 2p^6 3s^2 3p^2$ is

a. mg
b. c
c. s
d. si
e. he

1. a probability electron density cloud found around a nucleus is best defined as a(n)

a. quantum
b. electron configuration
c. orbital.
d. orbit.

1. how many electrons can occupy the $s$ orbitals at each energy level?

a. two, if they have opposite spins
b. two, if they have the same spin
c. one
d. no more than eight

1. the letter designations for the four sublevels with the maximum number of electrons that can be accommodated in each sublevel are

a. $s$:$2$, $p$:$4$, $d$:$6$, and $f$:$8$.
b. $s$:$1$, $p$:$3$, $d$:$5$, and $f$:$7$.
c. $s$:$2$, $p$:$6$, $d$:$10$, and $f$:$14$.
d. $s$:$1$, $p$:$2$, $d$:$3$, and $f$:$4$.

1. which of the following statements is false about the periodic table

a. the $p$ \block\ has 6 columns
b. group 8a is also called the noble gases
c. all rows are families
d. magnesium is both in the 3rd row and has valence electrons in $n$=$3$

Explanation:

Question 31

Step 1: Calculate total electrons

Sum the exponents in the electron configuration \(1s^2 2s^2 2p^6 3s^2 3p^2\). So \(2 + 2 + 6 + 2 + 2 = 14\).

Step 2: Identify element with atomic number 14

The atomic number (number of protons, equal to electrons in neutral atom) is 14. Silicon (Si) has atomic number 14. Mg (12), C (6), S (16), He (2) don't match.

• Quantum: A discrete quantity, not related to electron density cloud.
• Electron configuration: Arrangement of electrons in orbitals, not the cloud.
• Orbital: Defined as the probability electron density cloud around nucleus.
• Orbit: Old model, circular path, not a probability cloud.

• The s orbital can hold a maximum of 2 electrons, and they must have opposite spins (Pauli exclusion principle). Same spin electrons can't occupy the same orbital. One electron is less than max, and "no more than eight" is for outer shell (octet), not s orbital.

Answer:

d. Si

Question 32