Grade 10 · Science · Chemistry

10th grade Write formulas for ionic compounds worksheet

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Write formulas for ionic compounds

Grade 10 Science Worksheet - Building Confidence

NameDate

Circle the best answer, or write your answer on the line.

A sample holds 6 calcium ions, each +2. How many chloride ions, each −1, balance them, Ari?
A sample holds 15 magnesium ions, each +2. How many chloride ions, each −1, balance them, Bo?
A sample holds 4 aluminum ions, each +3. How many oxide ions, each −2, balance them, Esme?
Read this first
Dot diagram
Ions with charges that must add to zero. A calcium atom gives one electron to each of two chlorine atoms. That makes one Ca²⁺ and two Cl⁻: +2 − 1 − 1 = 0, so the formula is CaCl₂.
4.
On the card, how many electrons does calcium give away, Jun?
- 2
- 3
- 1
5.
On the card, why does CaCl₂ need two chloride ions, Kira?
- Calcium has two shells
- Two 1− charges balance one 2+
- Chlorine atoms come in pairs
6.
What charge does an oxide ion (group 16) have, Noah?
- +2
- −6
- −2
7.
What charge does an aluminum ion (group 13) have, Pia?
- +13
- −3
- +3
8.
What must the charges in an ionic formula add up to, Ren?
- One
- Zero
- The cation's charge
9.
Why is table salt's formula NaCl and not NaCl₂, Tala?
- +1 and −1 already add to zero
- Chlorine is lighter than sodium
- Sodium needs two chlorines
10.
Do the charges in MgO add to zero, Zee?
- Yes: +2 − 2 = 0
- No: it needs two O
- No: +2 + 2 = 4

Write formulas for ionic compounds. Every version has 10 questions, and the answer key prints on the second page.

I can give ion charges from the group: +1, +2, +3, −2, −1.
I can write formulas whose charges add to zero, using the least common multiple (Al₂O₃).
I can check a written formula's net charge and spot formulas that don't balance or aren't in lowest terms.
I can treat carbonate (CO₃²⁻) as one ion, as in chalk (CaCO₃).

Standard: none (TX)

ion: An atom or group with a charge

formula unit: The smallest whole-number ratio of ions in an ionic compound

least common multiple (LCM): The smallest number both charges divide into

polyatomic ion: A group of atoms with one shared charge, like CO₃²⁻

net charge: The sum of all the charges in a formula

Your child turned the charges upside down. Anions needed = cations × cation charge ÷ anion charge.

Your child added every charge as positive. Anion charges are negative, so subtract them: net = cations × charge − anions × charge.

Your child turned the ratio upside down. Use the formula's ratio: anions per cation = x ÷ y.

What is the most common mistake with write formulas for ionic compounds?

Your child turned the charges upside down. Anions needed = cations × cation charge ÷ anion charge.

Are these 10th grade science worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

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