Question

fill in the missing information:

| symbol | atom or ion?
check all that apply | number of protons | number of electrons |
| $\ce{sr^{2+}}$ | $\square$ neutral atom
$\square$ cation
$\square$ anion | $\square$ | $\square$ |
| $\square$ | $\square$ neutral atom
$\square$ cation
$\square$ anion | 9 | 9 |
| $\square$ | $\square$ neutral atom
$\square$ cation
$\square$ anion | 16 | 18 |

Explanation:

First Row (Sr²⁺)

Step1: Find atomic number of Sr

Strontium (Sr) has an atomic number of 38, so number of protons = 38.

Step2: Calculate electrons for Sr²⁺

A cation with +2 charge has lost 2 electrons. So electrons = 38 - 2 = 36.

Step3: Identify particle type

Since protons (38) > electrons (36), it's a cation.

Second Row (9 protons, 9 electrons)

Step1: Determine element

9 protons means element is fluorine (F).

Step2: Check particle type

Protons = electrons (9 = 9), so it's a neutral atom. Symbol is F.

Third Row (16 protons, 18 electrons)

Step1: Determine element

16 protons means element is sulfur (S).

Step2: Calculate charge

Electrons (18) > protons (16), so charge is 18 - 16 = -2. Symbol is S²⁻.

Step3: Identify particle type

Since electrons > protons, it's an anion.

Answer:

Symbol	neutral atom	cation	anion	number of protons	number of electrons
F	✅	❌	❌	9	9
S²⁻	❌	❌	✅	16	18