Year 8 Introduction to Chemistry

Identify which of the following best describes the structure of an atom. 

• A nucleus that is mostly empty space with charged particles circling around it

• A neutral nucleus circled by particles with positive and negative charges

• A positively charged nucleus circled by widely spaced negatively charged particles

• Atoms are the smallest particles of matter

An atom is electrically neutral if it has equal numbers of:

• neutrons and electrons

• protons and neutrons

• 

  protons and electrons

A particular soil is a mixture of sand, dead plant matter, water and air. The states of matter in this mixture are

• Solid and liquid only

• Liquid and gas only

• Solid only

• 

  Solid, liquid and gas

Oil and water can be separated using flotation because:

• Oil is more dense than water so floats on top

• Oil is more dense than water so sinks to the bottom

• Oil is less dense than water so floats on top

• Oil is less dense than water so sinks to the bottom

When an apple decays, it turns brown and the sugar it contains is converted into new substances.

Classify this type of change.

• Physical

• Chemical

Ice melts and forms water. Identify if the change is physical or chemical.

• Physical, because the molecules have been broken into pieces

• Physical, because the molecules have been re-arranged without any change in their type or number

• Chemical, because a new substance – liquid water – has formed

• Chemical, because the atoms have been re-arranged

The blue balls in Jars A, B and C represent particles.

Identify which states of matter they represent, in the order A, B, C.

• Solid, gas, liquid

• Gas, solid, liquid

• Solid, liquid, gas

• Liquid, gas, solid

Name the process of a liquid turning into a gas.

• Melting

• Evaporation or boiling

• Condensation

• Sublimation

Apply the particle model to explain the melting of ice cream.

Ice cream melts when its particles:

• gain energy, vibrate more, and begin to move around each other

• gain energy, speed up, and move far away from each other

• lose energy, slow down, and move into fixed positions

• lose energy, vibrate more, and begin to move around each other

The periodic table arranges all of the elements in order of increasing:

• atomic number

• abundance

• reactivity

• mass number