c1 atoms, elements and compounds

Question 1

what is an atom?

Answer 1

the smallest particle of a substance to exist

Question 2

what are compounds?

Answer 2

Compounds are formed from elements by chemical reactions.
Chemical reactions always involve the formation of one or more
new substances

Question 3

how can you separate a compound?

Answer 3

Compounds
can only be separated into elements by chemical reactions

Question 4

what is a mixture?

Answer 4

A mixture consists of two or more elements or compounds not
chemically combined together

Question 5

a feature of mixtures?

Answer 5

they have properties of the substances within the mixture

Question 6

a feature of compounds?

Answer 6

they have different properties to the substances within the compound

Question 7

how can mixtures be seperated?

Answer 7

1) filtration
2) chromatography
3) distillation
4) fractional distillation
5) crystallisation

Question 8

describe the process of filtration

Answer 8

1) make cone shape with filter paper
2) place it upside down in a beaker
3) pour solution (slowly) into the cone
- insoluble particles will not pass through the filter paper, only dissolved ions will

Question 9

describe the process of chromatography

Answer 9

1) at the near bottom of chromatography paper draw a straight line of pencil (pencil doesnt dissolve with the ink)
2) place a small dot of the ink you want to separate on the line
3) pour warm water in a beaker and put the chromatography paper inside, making sure the level of the water is just beneath the line

Question 10

describe the process of distillation

Answer 10

1) pour liquid into the distilling flask and heat with a bunsen burner until the bp of one of the substances
2) one substance will then evaporate and travel to the condensing tube which will turn it back to liquid
3) the liquid will then pour out into an empty beaker

Question 11

describe the process of fractional distillation

Answer 11

1) heat the substances in the mixture
2) they will evaporate at their bp, and travel up the factional tube
3) they will condense back as it gets cooler as they travel up and 4) the substances with the lowest bp will continue to travel up, go into the condensing rube and return to liquid state
5) change the beaker and repeat while heating the substances in the mixture at a higher temp

Question 12

describe the process of crystallisation

Answer 12

1) pour solution in an evaporating basin
2) warm the basin by placing it over a hot water bath OR very weak flame
3) stop heating after crystals form on the edges of the basin
4) keep stored in a cool and dry area

Question 13

timeline of the development of the atom?

Answer 13

1) belief that atoms where tiny spheres which could not be divided, however this changed with the discovery of electrons
2) J.J Thompson discovered the ‘plum pudding’ model
3) scientists carried out the ‘alpha scattering experiment’
4) from the conclusions drawn from the ASE, the nuclear model was introduced
5) Bohr discovered that electrons orbit the nucleus at specific distances
6) chadwick discovered neutrons

Question 14

describe the alpha scattering experiment

Answer 14

1) scientists took a piece of gold (gold was used specifically because it could be hammered into a very thin sheet, just a couple atoms thick)
2) scientists then fired tiny (positive) alpha particles at the sheet
- most particles passed straight through the atoms, implying that the atom was mainly made up of space
- sometimes it deflected direction as it passed through, implying that there has to be a positive charge in the centre of the atom
- sometimes it bounced straight back, implying that the centre is dense (we now call this, the nucleus)

Question 15

sizes of the atom

Answer 15

radius= 0.1nm (1x10^-10)
radius of nucleus= 1x10^-14)
protons and neutrons= 1
electrons= very small

Question 16

why do atoms have no overall charge?

Answer 16

they have the same amount of electrons and protons

Question 17

what is atomic number?

Answer 17

the number of protons in an atom

Question 18

what is a relative atomic mass?

Answer 18

an average value that
takes account of the abundance of the isotopes of the element

Question 19

equation for relative atomic mass?

Answer 19

(mass of isotope 1 x abundance of isotope 1) + (mass of isotope 2 x abundance of isotope 2) // 100

Question 20

how are the elements arranged in the periodic table and why are they arranged that way?

Answer 20

arranged in order of atomic
(proton) number and so that elements with similar properties are in
columns, known as groups. The table is called a periodic table
because similar properties occur at regular intervals

Question 21

similarities between elements in the same group?

Answer 21

1) same number of electrons in their outer shell
2) have similar chemical properties

Question 22

development of the periodic table

Answer 22

Before the discovery of protons, neutrons and electrons, scientists
attempted to classify the elements by arranging them in order of
their atomic weights.
The early periodic tables were incomplete and some elements were
placed in inappropriate groups if the strict order of atomic weights
was followed.
Mendeleev overcame some of the problems by leaving gaps for
elements that he thought had not been discovered and in some
places changed the order based on atomic weights.
Elements with properties predicted by Mendeleev were discovered
and filled the gaps. Knowledge of isotopes made it possible to
explain why the order based on atomic weights was not always
correct

Question 23

what type of element reacts to form positive ions?

Answer 23

metals

Question 24

what type of element reacts to form negative ions?

Answer 24

non metals

Question 25

properties of metals?

Answer 25

1) malleable 2) good conductors of heat and electricity 3) all solid at room temp apart from mercury 4) sonorous 5) ductile 6) lustrous 7) higher melting points

Question 26

properties of non metals?

Answer 26

1) bad conductors// dont conduct heat or electricity 2) not lustrous (shiny) 3) lower melting and boiling points

Question 27

how does the distance between the outer electron and the nucleus affect the reactivity of g7 elements?

Answer 27

group 7 gain electrons more easily if the outer shell is closer to their nucleus. as the forces of attraction between their positive nucleus and negative electron is stronger

Question 28

how does the distance between the outer electron and the nucleus affect the reactivity of g1 elements?

Answer 28

group 1 elements lose electrons more easily if the outer shell is further away from the nucleus as the forces of attraction bewteen the positive nucleus and the negative electron is weaker

Question 29

properties of noble gasses?

Answer 29

1) unreactive as they have a complete outer shell except for helium 2) boiling point increases as we go down the group as the inter-molecular forces become stronger 3) all gasses at room temp

Question 30

properties of alkali metals?

Answer 30

1) all have 1 electron in their outer shell 2) react vigorously with water 3) reactivity increases as you go down the group 4) soft 5) low densities 6) lower melting point as you go down the group

Question 31

describe the alkali reactions with water

Answer 31

1) react to produce a metal hydroxide + hydrogen. 2) reacts vigorously as you go down the group

Question 32

describe the alkali reactions with heated chlorine

Answer 32

1) react to form a white metal chloride salt 2) reacts vigorously as you go down the group

Question 33

describe alkali reactions with oxygen

Answer 33

1) reacts to form a metal oxide, peroxide or superoxide 2)

Question 34

properties of halogens?

Answer 34

1) less reactive as you go down the group 2) have 7 electrons in their outer shell 3) diatomics as they share an outer electron with eachother (covelant bond) 4) melting and boiling points increase as we go down the group

Question 35

what compounds do halogens form when they react with metals and no metals?

Answer 35

metals= ionic compounds non metals= covelant compounds

Question 36

can a more reactive halogen displace a less reactive halogen in an aqueous solution?

Answer 36

yes

Question 37

properties of transition metals

Answer 37

1) malleable 2) good conductors 3) can be used as catalysts 4) can form different ions 5) sonorous 6) form coloured compounds