Question

name: ____________ pd: __ chemistry u3l14_q3 ct module day 3 hw
** 14. which of the following shows the correct number of protons, neutrons, and electrons in a neutral cesium-134 atom?
(a)

protons	neutrons	electrons

(b)

protons	neutrons	electrons

(c)

protons	neutrons	electrons

(d)

protons	neutrons	electrons

** 15. $1s^2 2s^2 2p^6 3s^2 3p^6$
which of the following species has the electron configuration shown above?
(a) o
(b) ne
(c) $k^+$
(d) $cl^+$

Explanation:

for Question 14:

Step1: Find protons in cesium

Cesium atomic number = 55 → protons = 55

Step2: Calculate neutrons

Mass number = 134 → neutrons = 134 - 55 = 79

Step3: Electrons in neutral atom

Neutral atom: electrons = protons = 55

for Question 15:

Step1: Count total electrons

$1s^22s^22p^63s^23p^6$ → 2+2+6+2+6=18 electrons

Step2: Match species with 18 electrons

• O: 8 electrons; Ne:10; $K^+$:19-1=18; $Cl^-$:17+1=18. Both C and D have 18 electrons.

Answer:

1. B. Protons:55, Neutrons:79, Electrons:55
2. C. $K^+$, D. $Cl^-$