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Flashcards in topic 1 (atomic structure..) Deck (21)
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1

atom

an atom is a very small thing

2

element

a single type of atom

3

compound

2 or more elements that are chemically combined

4

mixture

2 or more elements that are not chemically combined

5

chromatography

involves separation of a solvent and solid (pen dots on a piece of paper)

6

simple distillation

A method of separating mixtures based on differences in their volatilities in a boiling liquid mixture.

7

fractional distillation

Fractional distillation is the separation of a mixture into its component parts, or fractions. Chemical compounds are separated by heating them to a temperature at which one or more fractions of the mixture will vaporize.

8

crystallisation

separate soluble salt from solution

9

filtration

separating a liquid and a solid

10

electron energy levels

a specific number of electrons go on each shell

2,8,8,16...

11

alpha scattering experiment

In the experiment, positively charged alpha particles were fired at thin gold foil. Most alpha particles went straight through the foil. But a few were scattered in different directions. This evidence led Rutherford to suggest a new model for the atom, called the nuclear model

12

the plum pudding model

this suggested the atom was a ball of positive charge with negative electrons embedded in it

13

the nuclear model

niels Bohr explained electrons orbit the nucleus at fixed distances
the positive charge is due to protons
James Chadwick explains nucleus contains neutrons

14

atomic number

is the number of protons/electrons in an atom

15

mass number or atomic mass

is the number of protons plus neutrons in an atom

16

periodic table

the early periodic table in 1800s were arranged by atomic mass
Mendeleev did take the elements properties into count
Mendeleev left gaps and predicted new elements

17

properties of transition metals

high melting points.
high densities.
they form coloured compounds.
they (and their compounds) can act as catalysts.

18

group 0 elements

The group 0 elements, the noble gases, are all unreactive non-metal gases. They show trends in their physical properties.
All group 0 noble gases have eight electrons in the full outer shell, except helium just has the two, but still a full shell! The melting point of group 0 noble gases increases down the group. The boiling point of group 0 noble gases increases down the group.

19

group 1 elements

Alkali metals are grey solids with shiny silvery surfaces when freshly cut.

These surfaces turn dull when exposed to air.This is because alkali metals are very reactive.

They react rapidly with oxygen and water vapour in the air when exposed.

melting and boiling points decrease as you go down the group

20

group 7 elements

The halogens have low melting points and low boiling points.

they are diatomic molecules (meaning they come in two's)

they are highly reactive (mostly at the top)

increase in boiling point as you go down
used in sterilisation

21

who discovered what?

jams Chadwick discovered the nucleus
jj Thomson discovered electrons (plum pudding model)
Ernest Rutherford -nuclear model