According to Particle Theory, what happens to particles when heated?

They stop moving

They move faster

They shrink

They disappear

They move faster

Heating adds energy, so particles vibrate and move faster.

A substance made of one type of particle is called:

Mixture

Pure substance

Solution

Alloy

Pure substance

A pure substance contains only one type of particle (element or compound).

Which of the following is a mechanical mixture?

Salt water

Granite

Bronze

Oxygen gas

Granite

Granite is heterogeneous; you can see different parts.

Alloys are best described as:

Pure substances

Solutions of metals

Compounds

Mechanical mixtures

Solutions of metals

Alloys are homogeneous mixtures of metals, e.g., steel, bronze.

Which is a qualitative property?

Density

Colour

Mass

Melting point

Colour

Qualitative = descriptive, not numerical.

Which is a quantitative property?

Blue colour

Density

Smell

Texture

Density

Quantitative = measured with numbers.

Viscosity measures:

Resistance of a liquid to flow

Density of solids

Conductivity

Melting point

Resistance of a liquid to flow

Honey has high viscosity; water has low.

Which is a physical property?

Flammability

Density

Reactivity with acid

Rusting tendency

Density

Physical properties can be observed without changing the substance.

Rusting is a:

Physical change

Chemical change

–

–

Chemical change

Rusting creates a new substance (iron oxide).

Which is a clue of chemical change?

Ice melting

Salt dissolving

Gas bubbles forming

Cutting paper

Gas bubbles forming

Gas production indicates a new substance has formed.

What is a precipitate?

A gas in a reaction

A solid formed when 2 liquids react

An alloy

A solution

A solid formed when 2 liquids react

Precipitates are insoluble solids formed in reactions.

A block has mass = 60 g, volume = 30 mL. What is its density?

1 g/mL

2 g/mL

30 g/mL

90 g/mL

2 g/mL

Density = mass ÷ volume = 60 ÷ 30 = 2 g/mL.

In a Bohr diagram, the first shell holds max:

8 electrons

2 electrons

4 electrons

10 electrons

2 electrons

The first shell can hold a maximum of 2 e⁻.

Sodium (Na, Z=11, A=23). Electrons in the 3rd shell?

0

1

2

8

1

Electron config: 2, 8, 1 → 1 electron in 3rd shell.

Oxygen (O, Z=8, A=16). Neutrons?

6

8

10

16

8

Neutrons = Mass – Atomic Number = 16 – 8 = 8.