Topic 2: What is our world made of?

Question 1

Matter

Answer 1

Anything that has mass and takes up space

Question 2

Element

Answer 2

A pure substance that consists entirely of one type of atom and cannot be chemically broken into simpler substances

Question 3

Atom

Answer 3

The smallest unit of an element that retains its properties

Question 4

Molecule

Answer 4

The smallest unit of most compounds that displays the properties of that compound

Question 5

Compound

Answer 5

A substance made up of atoms of two or more different elements joined by chemical bonds

Question 6

Pure substance

Answer 6

A sample of matter (single element/compound) that has definite chemical and physical properties

Question 7

Mixture

Answer 7

A material composed of two or more substances that are physically mixed together but not chemically combined

Question 8

Melting point

Answer 8

The temperature and pressure at which a solid becomes a liquid

Question 9

Boiling point

Answer 9

The temperature and pressure at which a liquid becomes a gas

Question 10

Density

Answer 10

The ratio of the mass of a substance to its volume

Question 11

Reactivity

Answer 11

The capacity of a substance to combine with another

Question 12

Physical change

Answer 12

A change of matter from one form to another without change in chemical properties

Question 13

Chemical change

Answer 13

When one or more substances change into entirely new substances with different properties

Question 14

Evaporation

Answer 14

The change of state from a liquid to a gas

Question 15

Condensation

Answer 15

The change of state from a gas to a liquid

Question 16

Sublimation

Answer 16

The process in which a solid changes directly into a gas

Question 17

Fluid

Answer 17

A non-solid state of matter in which the atoms or molecules are free to move past each other – gas or liquid

Question 18

Plasma

Answer 18

A state of matter that consists of free-moving ions and electrons

Question 19

Energy

Answer 19

The capacity to do work. Measured in joules.

Question 20

Temperature

Answer 20

A measure of the average kinetic energy of the particles of an object

Question 21

Thermal energy

Answer 21

The total kinetic energy of a substance’s atoms

Question 22

Pressure

Answer 22

The amount of force exerted per unit area of a surface (F/A)

Question 23

Pascal

Answer 23

The SI unit of pressure (N/m^2)

Question 24

Viscosity

Answer 24

The resistance of a gas or liquid to flow

Question 25

Buoyant force

Answer 25

The upwards force that keeps an object immersed in or floating on a fluid

Question 26

Electron

Answer 26

A negatively charged particle, located in the space surrounding the nucleus

Question 27

Nucleus

Answer 27

The center of an atom, which contains the protons and neutrons

Question 28

Isotope

Answer 28

One of two or more atoms of the same element that have the same number of protons, but different numbers of neutrons

Question 29

Valence electron

Answer 29

An electron that is found on the outermost shell of an atom and determines its chemical properties

Question 30

Photon

Answer 30

A particle of electromagnetic radiation that has zero rest mass and carries a quantum of energy