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1

list 4 factors that can speed up the rate of a reaction

1. increasing concentration
2. increasing surface area - decrease particle size
3. increase temperature
4. use a catalyst

2

formula for rate of reaction

Average rate = change in quantity/change in time

3

why does that average rate of a reaction decrease over time?

the reactants are being used up so the concentration of reactants are decreasing

4

what is a catalyst?

a substance that speeds up a chemical reaction but is not used up by the reaction

5

how are elements arranged in the periodic table?

in order of increasing atomic number

6

how are elements in the same group similar?

- they have the same number of outer electrons
- they have similar chemical properties
- they have the same valency

7

describe an atom

a nucleus containing protons and neutrons with electrons in orbit

8

what is the mass number of an atom?

the number of protons + neutrons

9

what is the atomic number of an atom?

the number of protons

10

how do you work out the number of neutrons in an atom?

mass number - the atomic number

11

what is the mass of an electron?

an amount so small its not worth working out

12

what is the charge of an electron?

-1

13

what is the mass of a proton?

1 atomic mass unit

14

what is the charge of a proton?

+1

15

what is the mass of a neutron?

1 atomic mass unit

16

what is the charge of a neutron?

0

17

what are isotopes?

atoms with the same atomic number but different mass number ( they have different numbers of neutrons)

18

what is the relative atomic mass of an element?

the average mass of an element

19

what is a covalent bond?

a shared pair of electrons holding non-metal atoms together

20

how are atoms in a covalent bond held together?

by the attraction between the positive nuclei and the shared pair of electrons

21

list the 7 diatomic elements

- nitrogen
- oxygen
- fluorine
- hydrogen
- iodine
- bromine
- chlorine

22

what does diatomic mean?

two atoms covalently bonded

23

what shape would a molecule with the formula XY have?

linear

24

what shape would a molecule with the formula XY^2 have?

angular

25

what shape would a molecule with the formula XY^3 have?

trigonal pyramidal

26

what shape would a molecule with the formula XY ^4 have?

tetrahedral

27

what is an ion?

an atom that has gained or lost electrons in charge ( they do this to be stable like the noble gasses)

28

ionic compounds are usually made from a metal and non-metal. which ion will be positively charged?

metal ion = positive
non-metal ion = negative

29

what is an ionic bond?

an electrostatic attraction between positive and negative ions

30

what structure do ionic compounds have?

crystal lattice
- each positive ion surrounded by a negative ion and each negative ion surrounded by positive ions