Front

What are electrons?

Back

The particles of atoms that carry a negative charge.

Front

What are protons?

Back

The particles of atoms that carry a positive charge.

Front

What are neutrons?

Back

The particles of atoms that do not carry a charge.

Front

What is the nucleus?

Back

The dense central core of an atom.

Front

What happens when aluminum is divided into smaller pieces?

Back

Eventually, the process produces an aluminum atom, the smallest piece of the aluminum element.

Front

Why do salt crystals disappear when mixed with water?

Back

Salt crystals separate, and the parts spread evenly among water molecules.

Front

How is the drying of a puddle explained at the molecular level?

Back

Water molecules are held loosely together in the liquid state. When surface molecules gain enough energy, they break free and enter the air as water vapor.

Front

What happens to a sealed balloon when heated?

Back

The balloon expands slightly and then bursts.

Front

Why does the cork pop out of a heated bottle?

Back

When gas particles gain energy, they move faster and exert greater pressure.

Front

What is air made of?

Back

Air is made of individual atoms and molecules that move separately from one another.