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 - Challenge Me

NameDate

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

Al₂O₃ has 3 oxide ions for every 2 aluminum ions. A sample holds 4 aluminum ions. How many oxide ions does it hold, Ari?
CaCl₂ has 2 chloride ions for every 1 calcium ion. A sample holds 5 calcium ions. How many chloride ions does it hold, Bo?
Al₂O₃ has 3 oxide ions for every 2 aluminum ions. A sample holds 10 aluminum ions. How many oxide ions does it hold, Esme?
4.
Chalk is calcium carbonate. What is its formula, Jun?
- Ca(CO₃)₂
- CaCO₃
- Ca₂CO₃
5.
In CaCO₃, how is the carbonate part treated, Kira?
- As one ion with a 2− charge
- As a neutral molecule
- As four separate ions
6.
Why does CaCO₃ have one calcium for each carbonate, Luz?
- Calcium is heavier
- +2 and −2 balance
- Carbonate has three oxygens
7.
Milo writes magnesium oxide as Mg₂O₂ because each charge is 2. Agree or disagree?
- Agree: copy each charge as a count
- Disagree: reduce it to MgO
- Agree: 2 and 2 balance
8.
Which of these formulas is correct, Ren?
- Na₂Cl
- NaCl
- NaCl₂
9.
Which formula for calcium chloride is correct, Tala?
- CaCl₂
- CaCl
- Ca₂Cl
10.
Do the charges in MgCl₂ add to zero, Zee?
- No: it needs three Cl
- No: +2 − 1 = +1
- Yes: +2 − 2 = 0

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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