Topic 1 - Atomic Structure and the Periodic Table Flashcards

1
Q

What is an atom?

A

An atom is the smallest part of an element that can exist

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2
Q

What is an element?

A

An element is a substance of only one type of atom.

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3
Q

How are the elements listed
and approximately how
many are there?

A

They are listed in the periodic table; there are approximately 100

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4
Q

Elements can be classified into two groups based on their
properties; what are these groups?

A

Metals and non-metals

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5
Q

Elements may combine through chemical reactions to
form new products; what are these new substances called?

A

Compounds

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6
Q

What is a compound?

A

Two or more elements combined chemically in fixed proportions which can be represented by formulae

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7
Q

Do compounds have the
same properties as their
constituent elements?

A

No, they have different properties

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8
Q

What is a mixture? Does it have the
same chemical properties as its
constituent materials?

A

A mixture consists of two or more elements or compounds not chemically combined together; it does have the same chemical properties

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9
Q

What are the methods through
which mixtures can be separated
(there are five)? Do these involve
chemical reactions?

A

Filtration, crystallisation, simple distillation, fractional distillation and chromatography; they do not involve chemical reactions

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10
Q

Describe and explain simple
distillation.

A

Simple distillation is used to separate liquid from a solution – the liquid boils off and condenses in the condenser. The thermometer will read the boiling point of the pure liquid. Contrary to evaporation, we get to keep the liquid

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11
Q

Describe and explain
crystallisation/evaporation

A

Evaporation is a technique for separation of a solid dissolved in a solvent from a solvent (e.g. salt from H2O).
The solution is heated until all the solvent evaporates; the solids stays in the vessel.

Crystallisation is similar, but we only remove some of the solvent by evaporation to form a saturated solution (the one where no more solid can be dissolved). Then, we cool down the solution. As we do it, the solid starts to crystallise, as it becomes less soluble at lower temperatures. The crystals can be collected and separated from the solvent via filtration.

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12
Q

Describe and explain
fractional distillation

A

Fractional distillation is a technique for separation of a mixture of liquids.
It works when liquids have different boiling points.

The apparatus is similar to the one of simple distillation apparatus, with the additional fractionating column placed on top of the heated flask.

The fractionating column contains glass beads. It helps to separate the compounds.In industry, mixtures are repeatedly condensed and vapourised. The column is hot at the bottom and cold at the top. The liquids will condense at different heights of the column

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13
Q

Describe and explain
filtration

A

Filtration is used to separate an insoluble solid is suspended in a liquid.
The insoluble solid (called a residue) gets caught in the filter paper, because the particles are too big to fit through the holes in the paper.
The filtrate is the substance that comes through the filter paper.
Apparatus: filter paper + funnel.

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14
Q

Describe and explain
chromatography

A

Chromatography is used to separate a mixture of substances dissolved in a solvent.
In paper chromatography, we place a piece of paper with a spot containing a mixture in a beaker with some solvent. The bottom of the paper has to be in contact with the solvent. The solvent level will slowly start to rise, thus separating the spot
(mixture) into few spots (components)

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15
Q

What is a separating funnel?

A

A separatory funnel is an apparatus for separating immiscible liquids.
Two immiscible liquids of different densities will form two distinct layers in the separatory funnel.
We can run off the bottom layer (the liquid with greater density) to a separate vessel

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16
Q

Describe the plum-pudding
model

A

The atom is a ball of positive charge with negative electron embedded in it

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17
Q

Describe the Bohr/nuclear
model and how it came
about

A

The nuclear model suggests that electrons orbit the nucleus at specific distances (shells) – it came about from the alpha scattering experiments

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18
Q

Later experiments led to the
discovery of smaller, positive
particles in the nucleus; what are
these particles called?

A

Protons

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19
Q

What did the work of James
Chadwick provide evidence
for?

A

The existence of neutrons in the nucleus

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20
Q

Describe the structure of an
atom

A

The atom has a small central nucleus (made up of protons and neutrons) around which there are electrons

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21
Q

State the relative masses and
relative charges of the proton,
neutron and electron

A

Masses: 1, 1, very small ; Charges: 1, 0 , -1 (respectively)

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22
Q

Explain why atoms are
electrically neutral

A

They have the same number of electrons and protons

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23
Q

What is the radius of an
atom?

A

0.1 nm

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24
Q

What is the radius of a nucleus and
what is it compared to that of the
atom?

A

1 x 10-14 m and 1/10000

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25
Q

What name is given to the
number of protons in the
nucleus?

A

Atomic number

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26
Q

Atoms of the same element have
the same number of which particle
in the nucleus?

A

Protons

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27
Q

Where is the majority of
mass of an atom?

A

The nucleus

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28
Q

What is the mass number?

A

The total number of protons and neutrons

29
Q

How does one calculate the
number of neutrons using mass
number and atomic number?

A

Subtract the atomic number from the mass number

30
Q

What is an isotope? Do isotopes
of a certain element have the same
chemical properties?

A

Atoms of the same element (same proton number) that have a different number of neutrons.
They have the same chemical properties as they have the same
electronic structure

31
Q

What is the relative atomic
mass?

A

The average mass value which takes the mass and abundance of isotopes of an element into account, on a scale where the mass of 12C is 12

32
Q

Give the electronic configurations of He (2), Be (4), F (9), Na (11), and Ca (20) to demonstrate how shells are occupied by electrons.

A

2
2,2
2,7
2,8,1
2,8,8,2

33
Q

What are ions?

A

Ions are charged particles. They are formed when atoms lose electrons (positive ions) or gain (negative ions) electrons.

E.g. sodium positive ion, Na+, has an electronic configuration of 2,8 (same as Ne). An atom of sodium has lost one electron

34
Q

Compare the properties of
metals and non-metals

A
35
Q

What is formed when a
metal reacts with a
non-metal?

A

An ionic compound (made of positive and negative ions)

36
Q

What is formed when a
non-metal reacts with a
non-metal?

A

A molecular compound containing covalently bonded atoms.

Atoms share electrons, as opposed to transferring electrons between each other (cf. ionic compounds).

37
Q

Explain the following: solute, solvent, solution, miscible,
immiscible, soluble, insoluble.

A

A solute is a substance that is dissolved in a solvent. Together, they form a solution.

Miscible refers to the substances (particularly liquids) that mix together, e.g. water and alcohol. Water and oil are immiscible, i.e. they do not mix.

Soluble refers to the substance that can be dissolved in a solvent, e.g. salt in water. Insoluble substance won’t dissolve in a particular solvent.

38
Q

The columns of the periodic
table are called…?

A

Groups

39
Q

The rows of the periodic
table are called…?

A

Periods

40
Q

Are elements in the same
group similar or different?

A

They may have similar chemical properties, as they have the same number of outer shell electrons

41
Q

In terms of energy levels, what are
the differences between elements
of the same period?

A

They have the same number of energy levels

42
Q

Electrons occupy particular energy
levels, with each electron in an atom at a
particular energy level; which available
energy level do electrons occupy?

A

The lowest available energy level

43
Q

The elements of Group 0
are more commonly known
as…?

A

The noble gases

44
Q

What makes the periodic
table periodic?

A

Similar properties of elements occur at regular intervals

45
Q

Elements in the same group have the
same number of electrons in their outer
shell; what does this tell us about their
chemical properties?

A

They have similar chemical properties

46
Q

In terms of shells, what is the
difference between elements
in the same period?

A

They have the same number of shells

47
Q

What change in shell
number is seen as one
moves down a group?

A

The number of shells increases

48
Q

Early periodic tables were
incomplete and elements were
placed in inappropriate groups if
what was to be followed?

A

The strict order of atomic weights

49
Q

Knowledge of what made it
possible to explain why the order
based on atomic weights was not
always correct?

A

Isotopes

50
Q

Mendeleev overcame some
problems with the table by doing
what? He also changed the order
of some elements based on what?

A

Leaving gaps; atomic weights

51
Q

The majority of elements
are…?

A

Metals

52
Q

Elements that react to form
positive ions are…?

A

Metals

53
Q

Elements that do not form
positive ions are…?

A

Non-metals

54
Q

Elements in Group 1 are
known as…?

A

The alkali metals

55
Q

State three characteristics of
the Alkali Metals

A

All have one electron in their outer shell; have low density; are stored under oil (to prevent reactions with oxygen or water); are soft (can be cut with knife)

56
Q

How do Group 1 elements react
with non-metals? Why are these
reactions similar for the different
Group 1 elements?

A

They form ionic compounds which are soluble white solids which form colourless solutions – they all have one electron in their outer shell.

57
Q

How do Group 1 elements
react with water?

A

They release hydrogen and form hydroxides which dissolve to form alkaline solutions; react vigorously with water fizzing and moving around on the surface of the water.

58
Q

How does the reactivity
change moving down Group
1? Why?

A

Reactivity increases as the atoms get larger and the distance between the nucleus and the outer electrons increases and thus attraction from the nucleus decreases, allowing them to more easily lose electrons.

59
Q

State five characteristics of
Group 7

A
  • 7 electrons in outer shell
  • Coloured vapours
  • Diatomic molecules
  • Form ionic salts with metals
  • Form molecular compounds with non-metals
60
Q

State Group 7 elements and
their states of matter

A

Fluorine, F. F2 is a pale yellow gas.
Chlorine, Cl. Cl2 is a pale green gas.
Bromine, Br. Br2 is dark brown liquid
Iodine, I. I2 is a grey solid

61
Q

State three changes that
occur in Group 7 as one
moves down the group

A
  • Higher relative molecular mass
  • Higher melting and boiling point
  • Less reactive - less easily gain electrons
62
Q

A more reactive halogen displaces a less reactive
one from an aqueous solution of its salt; write the
equations and state the colour change seen when
chlorine reacts with sodium bromide and when
chlorine/bromine reacts with sodium iodide.

A
63
Q

A more reactive halogen displaces a less reactive
one from an aqueous solution of its salt; explain the
trend in reactivity of halogens in these reactions

A

Reactivity decreases down the group. As we go down the group, the atoms get larger, so an incoming electron will be less tightly held by the attractive forces from the nucleus. That’s why Cl2 displaces Br and I.

64
Q

Compare Group 1 metals and
transition metals

A

Group 1 metals and transition metals are heat and electricity conductors. They are shiny when polished and form ionic compounds with non metals.

Transition metals have higher densities and higher melting points than Group 1 metals. They are less reactive and harder than Group 1 metals

65
Q

State three common
characteristics of transition
metals

A
  • Ions with different charges
  • Coloured compounds
  • Catalytic propertie
66
Q

What is a catalyst?

A

A catalyst is a chemical substance that increases the rate of a
chemical reaction.

It is not used up over the course of the reaction.

67
Q

State the colours of flames
observed when lithium,
sodium, and potassium burn
in oxygen

A

Crimson-red, Li
Yellow-orange, Na
Lilac, K

68
Q

Describe the properties of noble
gases. Discuss the trend in boiling
point down the group

A

Non-metals, gases, low boiling points, unreactive (full outer shell; they don’t easily accept or lose electrons).

The boiling point increases down the group, as the atoms get heavier.