Chapter 5 ( Strctures And Properties Of Material )

Question 1

What is an element?

Answer 1

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

Question 2

What is a compound?

Answer 2

A compound is a pure substance containing two or more
elements that are chemically combined in a fixed ratio.

Question 3

How can compounds be separated into constituents?

Answer 3

1. thermal decomposition — exposing the compound to strong heat
2. electrolysis — passing electric current through the
   compound.

Question 4

One similarity in ways to separate compounds?

Answer 4

The methods used are chemical processes to separate the chemically combined elements

Question 5

What are mixtures?

Answer 5

Mixtures do not have substances in fixed ratios and can consist of elements and/or compounds.

Question 6

Why can mixtures be separated by physical separation techniques?

Answer 6

Because they are physically combined not chemically combined meaning there was no chemical reaction or new substance formed

Question 7

How can mixtures be separated?

Answer 7

filtration;
o chromatography; and
o distillation ( fractional and simple )

Question 8

Difference between mixtures and compounds

Answer 8

Compounds chemically combined causing chemical reaction to occur and new substance formed but mixture physically combined so new new substance or reaction occur.

Compounds need to be separated chemically but mixtures can be separated using physical separation techniques

Question 9

Compound and element melting boiling point

Answer 9

Fixed

Question 10

Mixture melting boiling point

Answer 10

Range of temperatures because mixtures contain compounds or elements physically mixed together no chem combine

Question 11

Property of ionic substances?

Answer 11

Ionic substances have high melting boil point
Hard but brittle
Soluble in water
Insoluble in organic solvents

Question 12

Does charge affect melt or boil?

Answer 12

The larger the charge the higher the melting and boiling points

Question 13

What are giant molecules? ( giant molecules = giant covalent molecules )

Answer 13

giant network of atoms that are bonded by strong covalent bonds to form giant molecular structures.

Question 14

What is an allotrope?

Answer 14

different forms of the same element with different structural arrangement of atoms

Question 15

Diamond properties

Answer 15

Hard and high melting point
No electrical conductivity

Question 16

Why diamond is hard and hard high melting point?

Answer 16

large amount of
energy is required to
overcome the strong
covalent bonds between
atoms in the material

Question 17

Why diamond don’t conduct electricity?

Answer 17

Does not conduct electricity due to the
absence of mobile ions or electrons as all 4
electrons of each carbon atom are involved in
bonding

Question 18

Diamond structure?

Answer 18

Each carbon atom is covalently bonded to
four other carbon atoms to form a three-
dimensional tetrahedral structure.

Question 19

What does it mean when all 4 carbon atoms bonded?

Answer 19

No free electrons left for delocalisation

Question 20

What is diamond

Answer 20

Allotrope of carbon

Question 21

What is graphite

Answer 21

Allotrope of carbon

Question 22

Structure of graphite?

Answer 22

Each carbon atom is
covalently bonded to three
other carbon atoms to form
a three-dimensional layered
structure, consisting of
hexagonal rings of carbon
atoms.

Question 23

Graphite property?

Answer 23

High melting point
Soft and slippery
Good electrical conductor and thermal

Question 24

Why graphite has high melting point?

Answer 24

large amount of energy is
required to overcome the strong covalent bonds
between atoms

Question 25

Why graphite soft and slippery

Answer 25

layers of atoms are held by
weak intermolecular forces of attraction, these
layers can slide over each other when a force is
applied.

Question 26

Why graphite good electrical and thermal conductor?

Answer 26

each carbon atom has one electron not used in bonding. Presence of delocalised electrons along the layers act as mobile charge carriers.

Question 27

What is strcture property and all of silicon dioxide?

Answer 27

SAME AS DIAMOND

Question 28

What is solubility of giant molecules?

Answer 28

Insoluble in water and organic solvents. ALL GIANT MOLECULES

Question 29

What does it mean when something is gas/liquid at room temp?

Answer 29

SUPER LOW BOILING POINT = SIMPLE MOLECULE

Question 30

Fixed melting boiling point means what

Answer 30

Pure elements and compounds

Question 31

Separated by physical methods means?

Answer 31

Mixture present

Question 32

High melting boiling point mean?

Answer 32

Large amount of energy required to overcome opposite charge forces of attraction/ covalnet bonds between atoms .

It’s metals, giant covalent compounds, ionic compounds

Question 33

Can conduct electricity in molten/liquid and aqueous state only?

Answer 33

IONIC COMPOUND

Question 34

Can conduct electricity no matter the state?

Answer 34

Metals and graphite

Question 35

Can’t conduct electricity for the love of god? Why

Answer 35

Covalent substances because covalent molecules are made up of atoms which are electrically neutral making the substance electrically neutral hence no charged particles are present to carry electrical charge.

Question 36

Soft and slippery means what?

Answer 36

GRAPHITE