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Flashcards in Chemistry Deck (143)
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1

What are elements

A substance that is made of only one sort of atom

2

How many different elements are there

Around 100

3

Where are elements shown

In the periodic table

4

What do the groups in the periodic table contain

Elements with similar properties

5

What are atoms of each element represented by

A chemical symbol

6

What are atoms nucleus' made up of

Protons, neutrons and around which there are electrons

7

What are the relative electrical charges

Proton +1
Neutron 0
Electron -1

8

What are the number of electrons equal to in an atom

The number of protons in the nucleus

9

Do atoms have an overall electric charge

No

10

What do all atoms of a particular element have

The same number of protons

11

What do atoms of different elements have

Different numbers of protons

12

What is an element's atomic number

The number of protons it has

13

What is an element's mass number

The sum of the protons and neutrons

14

What do electrons occupy

Particular energy levels. Each electronic an atom is at a particular energy level (in a particular shell). The electrons in an atom occupy the lowest available energy levels (innermost available shells)

15

What do elements in the same group in the periodic table have

The same number of electrons in the highest energy level (outer electrons) and this gives them similar chemical properties

16

What are noble gases

Elements in group 0

17

Why are noble gases unreactive

Their atoms have stable arrangement of electrons

18

What happens when elements react

The atoms join in with other atoms to form compounds. This involves giving, taking or sharing electrons to form ions or molecules.

19

What do compounds formed of metals and non-metals consist of

Ions

20

What are compounds formed from non-metals consist of

Molecules

21

How are the atoms held together in molecules

By covalent bonds

22

What can chemical reactions be represented by

Word equations or by symbol equations

23

Why are the mass of the products equal to the mass of the reactants in a chemical reaction

No atoms are lost or made during a chemical reaction

24

Why is it economical to extract metal from ores

What is contained in the metal. The economics of extraction may change over time

25

What happens before metal is extracted and purified

Ores are mined and may be concentrated

26

Where are unreactive metals such as gold found

In the earth as the metal itself

27

What do metals found as compounds require

Chemical reactions to extract the metal

28

What metals can be extracted from their oxides by reduction with carbon

Metals that are less reactive than carbon e.g. Iron oxide is reduced in the blast furnace to make iron

29

Which metals are extracted by electrolysis of molten compounds

Metals that are more reactive than carbon, such as aluminium

30

Why are certain metals expensive

The use of large amounts of energy in the extraction of them