Atomic Foundations of Matter: common misconceptions

If your child says… “Some mass disappears during a reaction.”

Ask together

Which atoms have disappeared when you count each kind again?

What’s true

A sealed reaction preserves total mass because no atoms enter, leave or disappear.

If your child says… “Pure water can have any ratio of hydrogen to oxygen.”

Ask together

Do both elements’ masses increase by the same factor?

What’s true

Changing the sample size does not change a pure compound’s element proportions.

If your child says… “One atom gives its electron away.”

Ask together

Does the shared pair interact with one nucleus or both?

What’s true

Both atoms share the electron pair in this covalent bond.

If your child says… “Salt must have an overall charge because its ions are charged.”

Ask together

What charge remains after each positive charge cancels a negative charge?

What’s true

The ions’ positive and negative charges balance across the compound.

If your child says… “One ion of each is enough.”

Ask together

What charge remains with one magnesium ion and only one chloride ion?

What’s true

Equal ion counts do not necessarily balance their charges.

If your child says… “The ions already flow through solid salt.”

Ask together

Can an ion travel across the solid while remaining around its position?

What’s true

Solid salt’s ions vibrate around their positions but cannot travel through the solid.

If your child says… “Sharing electrons always makes a substance hard to melt.”

Ask together

Does melting separate whole water molecules or split each molecule’s atoms apart?

What’s true

Small molecular substances often melt easily because attractions between their molecules are weak.

If your child says… “I count each element only once.”

Ask together

Which hydrogen atom would disappear from your calculation if you counted hydrogen only once?

What’s true

Both calculations include every atom indicated by the formula.