PAGE 9 — States of Matter & PAGE 10 — Phase Changes & PAGE 11 — Density & Specific Heat

What are the three main states of matter?

Solid, liquid, gas.

What determines the state of matter?

Particle arrangement and energy.

How are particles arranged in a solid?

Tightly packed, fixed shape, fixed volume.

How are particles arranged in a liquid?

Close together but able to move, no fixed shape, fixed volume.

How are particles arranged in a gas?

Far apart, move freely, no fixed shape or volume.

Which state has the strongest intermolecular forces?

Solids

Which state has the weakest intermolecular forces?

Gases.

What is melting?

Solid → liquid (energy absorbed)

What is freezing?

Liquid → solid (energy released).

What is evaporation?

Liquid → gas (energy absorbed).

What is condensation?

Gas → liquid (energy released).

What is sublimation?

Solid → gas (energy absorbed).

What is deposition?

Gas → solid (energy released).

Which state has the highest kinetic energy?

Gas

Which state has the lowest kinetic energy?

Solid

What happens to particle motion when temperature increases?

Particles move faster

What happens to particle motion when temperature decreases?

Particles move slower

Which phase changes absorb energy?

Melting, evaporation, boiling, sublimation

Which phase changes release energy?

Freezing, condensation, deposition.

What happens to particle motion when energy is absorbed?

Particles move faster and spread out.

What happens to particle motion when energy is released?

Particles move slower and come closer together.

What is latent heat?

Energy used to change phase, not temperature.

Does temperature change during a phase change?

No, temperature stays constant until the change is complete.

Is ice more or less dense than liquid water?

Less dense

Why is ice less dense than liquid water?

Water molecules form a rigid crystal structure that spreads them apart.

Does ice float or sink in water?

Floats (because it’s less dense).

What happens to water molecules when water freezes?

They expand and move farther apart.

What is the density of liquid water?

About 1.0 g/mL.

What is the density of ice?

About 0.9 g/mL (less than water).

Why is the density of ice important for life?

Floating ice insulates water below, allowing aquatic life to survive winter.

Does water expand or contract when it freezes?

Expands

What causes water to expand when freezing?

Hydrogen bonding locks molecules into a spaced‑out lattice.

What is the formula for density?

Density = Mass ÷ Volume

What are the units of density for solids and liquids?

g/mL or g/cm³

What are the units of density for gases?

g/L

How do you find mass if you know density and volume?

Mass = Density × Volume

How do you find volume if you know mass and density?

Volume = Mass ÷ Density

If an object has a density greater than 1.0 g/mL, will it float or sink in water?

Float

What happens to density if mass increases but volume stays the same?

Density increases

What happens to density if volume increases but mass stays the same?

Density decreases

What is specific heat?

The amount of energy needed to raise 1 g of a substance by 1°C.

What is the formula for specific heat?

q = m · c · ΔT

In the formula q = m·c·ΔT, what does q represent?

Heat energy (in joules or calories).

In the formula q = m·c·ΔT, what does m represent?

Mass (in grams).

In the formula q = m·c·ΔT, what does c represent?

Specific heat.

In the formula q = m·c·ΔT, what does ΔT represent?

Change in temperature (final − initial).

Does water have a high or low specific heat?

High specific heat.

What does high specific heat mean?

It takes a lot of energy to change the temperature.

Why does water heat up and cool down slowly?

Because it has a high specific heat.

Which heats up faster: metal or water?

Metal (low specific heat).

What happens to temperature when heat is added to a substance with low specific heat?

Temperature rises quickly.

What happens to temperature when heat is added to a substance with high specific heat?

Temperature rises slowly.