Question 2 options:
potassium forms ions with a charge of +1 (ka+). iodine forms ions with a charge of -1. selenium forms ions with a charge of -2 (

imagine that potassium ions and selenide ions combine to form potassium selenide. what numbers would be in the place of x and y in:

kxsey

(use the number 1 even if it isn't strictly necessary)
x= y=

K₂Se₁

Explanation:

Potassium selenide is ionic compound.

Ionic compound:

Ionic compounds are formed by the positive and negative ions but over all compounds are neutral, because total negative charges are equal to the positive charges and cancel the effect of each other.

Potassium lose its one electron and form cation i.e K⁺

while selenium required two more electron two complete the octet thus show -2 charge.

In given compound the negative and positive charge must be equal to make the compound over all neutral. That's why two potassium atoms combine to create +2 charge and to cancel -2 thus over all compound will becomes neutral.

K₂²⁽⁺¹⁾ Se⁻²  = K₂Se₁

The name of compound will be potassium selenide.

The cation is written first and anion is written after the cation.

atomic mass = 39

number of neutrons = 20

number of protons= 19

electronic configuration = 1s2 2s2 2p6 3s2 3p6 4s1

the number of electron in first shell = 2

number of electrons in n=3 shell = 8