Science Substances Sem 2

Question 1

Atoms

Answer 1

• Splitting Atoms creates nuclear power and atomic bombs.
• Smashing atoms together is where the sun gets energy from
• Made up of protons, neutrons and electrons
  Protons and neutrons form the nucleus together

Question 2

Metallic Metals

Answer 2

Elements that are metal. They have the following properties:
- Solids at room temperature (Except for
Hg)
- Can be made shiny or lustrous
- Conduct heat and electricity
- Can be beaten into shape or stretched into wire
Melts at very high temperatures (except for Hg)

Question 3

Non metallic Elements

Answer 3

19 non-metals. These have the folliwing properties:
- Dull, not shiny
- Breaks or crumbles when bent
- Melts at low temperature
Do not conduct heat or electricity

Question 4

Metalloids

Answer 4

A metalloid is a type of chemical element which has a preponderance of properties in between, or that are a mixture of, those of metals and nonmetals.

Question 5

Alkali Metals

Answer 5

Group 1. Very reactive in water

Question 6

Alkaline earth Metals

Answer 6

Group 2. Less reactive than alkali metals but still have all the metal properties

Question 7

Transition Metals

Answer 7

In the block between group 2 and 13. They have metallic properties. Have many interesting properties and many form colorful compounds

Question 8

Halogens

Answer 8

Group 17. They are very reactive. From left to right: Chlorine (gas), Bromine (liquid) and Lodine (solid)

Question 9

Noble Gases

Answer 9

Group 18. All very unreactive but glow when exposed to electricity under special conditions

Question 10

Monatomic Elements

Answer 10

An element that is made up of many individual atoms. Only 6 of these. Includes:
- Helium
- Neon
- Argon
- Krypton
- Xenon
- Radon

Question 11

Molecular Elements

Answer 11

Most non-metallic elements are made up of molecules. Molecules are clusters of 2 or more atoms bonded together. In these elements, all molecules are identical.

Question 12

Crystal Lattices

Answer 12

Are grid like structures

Question 13

Molecular Formula

Answer 13

Molecular formulas are formulas for substances that are molecules. Other compounds that aren’t formulas for substances that are not molecules can also have formulas that represent the atoms in the compound

Question 14

Mixtures

Answer 14

When two or more substances mix but do not form chemical bonds, it form a mixture. Air is a mixture of nitrogen, oxygen and carbon dioxide (a compound). Properties of a mixture is the same as the properties of its parts.

Question 15

Separating compounds

Answer 15

Breaking chemical bonds. Energy needed: Electricity, extreme heat, other chemicals

Question 16

Physical Change

Answer 16

Explains changes of state by looking at the relationship between how the particles move and attraction between the particles. Change between solids liquid and gases.

Question 17

Chemical Change

Answer 17

The key difference between a physical and chemical change is that new substances are produced during a chemical change.
Evidence:
- Solid precipitate out of solution
- An odour or bubbles or gases being released
- Light or heat being released
- A permanent change of colour
Electricity used or produced

Question 18

Colour Changes

Answer 18

This happens because the new substance produced by the chemical change is a different colour to what you started.

Question 19

Gas Produced

Answer 19

Produced during a chemical change may be observed as bubbles, a new smell or perhaps smoke

Question 20

Precipitate Forms

Answer 20

Any new solid is produced when two solutions are mixed.

Question 21

What energy is released

Answer 21

Energy plays an important role in chemical changes. Some release heat, light or both

Question 22

Energy is absorbed

Answer 22

Some chemical changes absorb heat, causing their surroundings to cool.

Question 23

Chemical Reactions

Answer 23

During chemical change, old substances disappear and new substances form. The only way this can occur is if the atoms in the old substances rearrange to form the new substances.

Question 24

Reactants

Answer 24

Old substances

Question 25

Products

Answer 25

New substances

Question 26

4 types of chemical reactions

Answer 26

Combustion, Photosynthesis, , Respiration, Corrosion

Question 27

Combustion

Answer 27

Is the term given to any chemical reaction that involves burning O2.

Question 28

Photosynthesis

Answer 28

Most biological chemical reaction. A series of chemical reactions that uses sunlight energy to convert H2O and CO2 into O2 and energy.

Carbon dioxide + Water ———– Oxygen + glucose

Question 29

Respiration

Answer 29

The process of obtaining energy from food.

Question 30

Corrosion

Answer 30

Type of reaction that can cause damage to metals.

Question 31

Flammability

Answer 31

Describes how easily a substance undergoes combustion.