c1 atoms, elements and compounds Flashcards

1
Q

what is an atom?

A

the smallest particle of a substance to exist

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2
Q

what are compounds?

A

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

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3
Q

how can you separate a compound?

A

Compounds
can only be separated into elements by chemical reactions

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4
Q

what is a mixture?

A

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

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5
Q

a feature of mixtures?

A

they have properties of the substances within the mixture

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6
Q

a feature of compounds?

A

they have different properties to the substances within the compound

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7
Q

how can mixtures be seperated?

A

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

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8
Q

describe the process of filtration

A

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

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9
Q

describe the process of chromatography

A

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

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10
Q

describe the process of distillation

A

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

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11
Q

describe the process of fractional distillation

A

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

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12
Q

describe the process of crystallisation

A

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

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13
Q

timeline of the development of the atom?

A

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

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14
Q

describe the alpha scattering experiment

A

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)

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15
Q

sizes of the atom

A

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

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16
Q

why do atoms have no overall charge?

A

they have the same amount of electrons and protons

17
Q

what is atomic number?

A

the number of protons in an atom

18
Q

what is a relative atomic mass?

A

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

19
Q

equation for relative atomic mass?

A

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

20
Q

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

A

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

21
Q

similarities between elements in the same group?

A

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

22
Q

development of the periodic table

A

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

23
Q

what type of element reacts to form positive ions?

A

metals

24
Q

what type of element reacts to form negative ions?

A

non metals

25
Q

properties of metals?

A

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

26
Q

properties of non metals?

A

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

27
Q

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

A

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

28
Q

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

A

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

29
Q

properties of noble gasses?

A

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

30
Q

properties of alkali metals?

A

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

31
Q

describe the alkali reactions with water

A

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

32
Q

describe the alkali reactions with heated chlorine

A

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

33
Q

describe alkali reactions with oxygen

A

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

34
Q

properties of halogens?

A

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

35
Q

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

A

metals= ionic compounds
non metals= covelant compounds

36
Q

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

A

yes

37
Q

properties of transition metals

A

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