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Flashcards in c1 Atomic Structure Deck (14)
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1

neutron

relative mass of 1

no charge

2

proton

relative mass of 1

1+ charge

elements are determined by number of protons

3

Isotopes

different form of the same element

different number of neutrons

same atomic number, different mass number

eg carbon-12 6 proton, 6 neutron
carbon-13 6 proton, 7 neutron

4

formula for relative atomic mass

sum of all (isotope abundance(%) * isotope mass)/abundance of all isotopes

5

compounds

two or more element in fixed proportions held together by chemical bonds

6

what is an element

if a substance only contains atoms with the same number fo protons it is an element

7

how many elements are there

about 100

8

John Dalton

early 19th century

atoms are different spheres and different spheres makes up elements

9

JJ thompson

1897

electron - his measurements of charge and mass showed that there are smaller particles

new theory known as the 'plum pudding model'

10

plum pudding model

ball of positive charge with negative electron in it

11

Ernest Rutherford and Ernest Marson

1909

alpha particle scatter experiments
few particles are deflected - tiny positively charged nucleus
cloud of negative electrons surrounds this nucleus - most of the atom is empty space
direct hit with the nucleus the particle were deflected backward, if near then it is deflected

came up with the nuclear model

(however the electrons would collapse if its like cloud. shells? bohr ?)
james chadwick

12

Bohr's nuclear model

contain shells

electron orbit the nucleus in fixed shells

this was supported by many experiments and explains lots of observations at the time

13

James Chadwick

neutrons

updated the model which made it pretty similar to today's nuclear model

14

electron shell rules

electron always occupy shells (energy levels)

lowest energy must be filled first

certain amount of electron in each shell:
2,8,8