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1

Relative atomic mass

The weighted average mass of an atom of an element compared to 1/12 the mass of carbon 12

2

Ar=

((Isotope mass)x(percentage))+(isotope mass x%)/100

3

Number of particles is

Moles x avogadros constant

4

the Greek atom

Democritus said that the division of matter must have a lower limit eventually you would end up with an indivisible particle an atom

5

Dalton's atomic theory

atoms are particles that make up elements, atoms cant be divided, all atoms of an element are the same, atoms of one element are different to atoms of another element

6

jj Thompson and electrons

discovered that cathode rays were a stream of particles(electrons) that were: negatively charged, can be deflected by magnets and electric fields, very small mass

7

plum pudding model

electrons float in a sea of positive charge - proposed by jj Thompson

8

Ernest Rutherford's gold leaf experiment

alpha particles were directed at a gold sheet, most not deflected, some deflected through large angles and few reflected. shows that most of an atom is empty space, positive charge in the middle with most of the mass, overall charges balance

9

Neil Bohr's model

altered Rutherfords model so electrons only follow certain paths otherwise they would spiral into the nucleus. explained emission and absorption spectra and the energy of electrons at different distances from the nucleus

10

what did Rutherford's discovery of the proton explain

explain the link between atomic number and x-ray frequencies

11

what are isotopes

when atoms of the same element have a different number of neutrons

12

why do isotopes of the same element have the same properties

chemical properties are linked to the number of electrons which is linked to the number of protons not neutrons

13

nitrate ion

NO3 -

14

carbonate ion

CO3 2-

15

sulfate ion

SO4 2-

16

hydroxide ion

OH-

17

ammonium ion

NH4+

18

zinc ion

Zn 2+

19

silver ion

Ag+

20

how to find the number of moles in a sample

moles=mass/molar mass

21

empirical formula

the simplest whole number ratio of atoms in a molecule

22

molecular formula

shows the number of atoms in a molecule

23

how to work out concentration

moles= concentration x volume

24

ideal gas equation

pv=nrt

25

simplified ideal gas equation

n=v/24

26

percentage yield=

(actual yield/theoretical yield)x100

27

reasons for low percentage yield

side reactions may occur, reaction may be at equilibrium, reactants may not be pure, some reactants may be left in apparatus

28

how to calculate atom economy

(mr of desired product/ mr of all products)x 100

29

water of crysalisation

when ionic compounds form there are often moles of water trapped in them shown as part of the formula after a dot

30

hydrated compounds

compounds containing water in their crystalline form