Question

fill in the missing information:

symbol	atom or ion? (check all that apply)	number of protons	number of electrons
ru	☐ neutral atom ☐ cation ☐ anion	☐	☐
☐	☐ neutral atom ☐ cation ☐ anion	9	10

Explanation:

For $\boldsymbol{\ce{Mg^{2+}}}$:

Step1: Determine atom/ion type

$\ce{Mg^{2+}}$ has a positive charge, so it's a cation (not neutral atom or anion).

Step2: Find number of protons

Magnesium (Mg) has an atomic number of 12, so protons = 12.

Step3: Find number of electrons

For a cation with $2+$ charge, electrons = protons - charge = $12 - 2 = 10$.

Step1: Determine atom/ion type

$\ce{Ru}$ (Ruthenium) has no charge, so it's a neutral atom (not cation or anion).

Step2: Find number of protons

Ruthenium has an atomic number of 44, so protons = 44.

Step3: Find number of electrons

In a neutral atom, electrons = protons = 44.

Step1: Determine atom/ion type

Electrons (10) > protons (9), so it's an anion (negative charge, not neutral atom or cation).

Step2: Identify the element

Atomic number = protons = 9, which is fluorine (F). The ion is $\ce{F^-}$ (since electrons = protons + 1, charge = $-1$).

Answer:

(for $\ce{Mg^{2+}}$):

• atom or ion: cation (check cation box)
• number of protons: 12
• number of electrons: 10

For $\boldsymbol{\ce{Ru}}$: