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Flashcards in Chemistry 5 Deck (67)
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How do you work out the amount of neutrons an element has ?

Mass number - atomic number

1

How are compounds formed ?

When two or more elements are chemically combined. It is difficult to separate this into the original elements

2

What is an isotope ?

Different atomic forms of the same element, which have the SAME number of PROTONS but a DIFFERENT number of NEUTRONS

3

Why do isotopes have to have the same number of protons ?

Because otherwise they are different elements altogether

4

Name 2 examples of popular isotopes

Carbon-12 and Carbon-14

5

What is the difference between carbon-12 and Carbon-14 ?

Carbon-14 has two more neutrons
(a mass number of 14)

6

Describe ionic bonding

When atoms lose or gain electrons to form charged particles called ions. They are strongly attracted to each other because opposite charges attract

7

When elements lose their electrons they become ions, which means ...

They react easily and quickly with an ion that has an opposite charge

8

What structure do ionic compounds have ?

Regular lattice structures

9

Describe an ionic compounds structure

It is a closely packed regular lattice arrangement. There are very strong forces of electrostatic attraction caused by the opposite charges attracting

10

Why do ionic compounds have high melting and boiling points ?

A large amount of energy is needed to overcome the high attraction

11

When ionic compounds melt, what can they do ?

Carry electric current

12

What happens when ions are added to water ?

They dissolve and the ions separate leaving them free to move

13

What groups of the periodic table are most likely to form ions ?

1&2 and 6&7

14

What do ionic compounds contain ?

A positively charged part and a negatively charged point

15

What is the overall charge of every compound ?

Zero

16

How can you work out the formula of an ionic compound ?

Look at the charges of each components and remember that when added together they must equal 0

17

What is covalent bonding ? Why is it done ?

When atoms share electrons in their outer shells. It means both atoms have full outer shells

18

Substances with covalent bonds can either be .....

Simple molecules or giant covalent structures

19

Describe simple molecules

• form very strong covalent bonds
• the forces of attraction between molecules are weak (intermolecular)

20

Why are simple molecular substances easy to break down ?

Their weak intermolecular forces can be broken down easily

21

Give three examples of simple molecular substances

• Chlorine
• Oxygen
• Water

22

Give three examples of giant covalent structures

• Diamond
• silicon dioxide (silica)
• Graphite

23

Are giant covalent structures similar to giant ionic structures ?

Yes, except there are no charge ions. The atoms are bonded by very strong covalent bonds

24

Do giant covalent structures conduct electricity ?

No, not even when molten. However graphite is an exception to the rule

25

Describe a diamonds formation and features

Each carbon atom has four covalent bonds forming a very rigid structure. It makes it the hardest natural substance

26

What is silica comprised of ?

Silicon and oxygen, this is what sand is made of

27

How does a pencil work ?

Each carbon atom in graphite only forms three covalent bonds. The layers of graphite can slide over each other and therefore rubbed onto paper

28

Why is graphite the only non-metal to conduct heat and electricity ?

Each carbon atom has a delocalised free electron which carries the heat or electricity through the material

29

What are free electrons ?

They come from the outer shell of every metal atom. They are free o move throughout the structure.