Chapter 4 - Elements, Compounds And Mixtures

Question 1

What are metalloids?

Answer 1

Metalloids are elements that have properties of both metals and non-metals.

Question 2

What are some physical properties of metals? (9)

Answer 2

1. Shiny (lustrous) appearance
2. Solid at room temperature pressure (rtp) except mercury
3. Malleable (can be hammered into different shapes without breaking)
4. Sonorous (makes ringing sound when struck)
5. Ductile (can be drawn into thin wires)
6. High melting and boiling points except for group I elements
7. Good conductors of heat
8. Good conductors of electricity in solid and molten state
9. High density

Question 3

What are some physical properties of non-metals?(6)

Answer 3

1. Dull appearance if solid (non/lustrous)
2. Either gases, volatile (vaporize easily) liquids or solid with low melting point
3. Brittle if solid
4. Low melting points and boiling points (except carbon and silicon)
5. Poor conductor of heat (except carbon in form of graphite and diamond)
6. Poor conductors of electricity

Question 4

What do elements exist as?

Answer 4

Atoms or molecules.

Question 5

What is an atom?

Answer 5

Atom is the smallest particle of an element that HAVE the chemical properties of that element. It is the building block of an element.

Question 6

What is a molecule?

Answer 6

A molecule is a group of two or more atoms that are chemically combined together.

Question 7

What is a compound?

Answer 7

A compound is a substance which is made up of two or more different elements chemically combined together in a fixed ratio.

Question 8

What is a characteristic of a compound?

Answer 8

The properties of a compound are different from its constituent element.

Question 9

How can compounds be broken down into simpler substances?

Answer 9

Thermal decomposition or electrolysis

Question 10

What are mixtures?

Answer 10

Mixtures are formed when two or mote substances are added together but not chemically combined.

Question 11

What are differences between compounds and mixtures?(4)

Answer 11

S - the components of a mixture can be separated by physical methods while elements in a compound can only by separated by chemical processes.

P - the chemical properties of a mixture are the sane as its components while physical and chemical properties of a compound are different from its elements.

E- No chemical reaction and little or no energy change occurs when a mixture is formed while chemical reaction and energy change takes place when a compound is formed.

C - Components of a mixture can be mixed in any proportion while elements in a compound are always combined in a fixed proportion.

Question 12

What is an element?

Answer 12

An element is a pure substance that cannot be broken down into two or more simpler substances by electricity or by chemical processes.