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Chemistry > Unit 1 - Atomic Structure and the Periodic Table > Flashcards

Unit 1 - Atomic Structure and the Periodic Table Flashcards

1
Q

What is an atom?

A

An atom is the smallest part of an element what 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 element 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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6
Q

Do compounds have the same properties as their
constituent elements?

A

No, they have different properties.

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7
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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8
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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9
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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10
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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11
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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12
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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13
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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14
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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15
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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16
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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17
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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18
Q

What did the work of James Chadwick provide
evidence for?

A

The existence of neutrons in the nucleus

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19
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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20
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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21
Q

Explain why atoms are electrically neutral.

A

They have the same number of electrons and protons

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22
Q

What is the radius of an atom?

A

0.1 nm

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23
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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24
Q

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

A

Atomic number

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25
Q

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

A

Protons

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26
Q

Where is the majority of mass of an atom?

A

The nucleus

27
Q

What is the mass number?

A

The total number of protons and neutrons

28
Q

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

A

Subtract the atomic number from the mass number

29
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

30
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.

31
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.

32
Q

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

A

An ionic compound (made of positive and negative ions)

33
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).

34
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.

35
Q

The columns of the periodic table are called?

A

Groups

36
Q

The rows of the periodic table are called…?

A

Periods

37
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

38
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

39
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

40
Q

The noble gases

A

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

41
Q

What makes the periodic table periodic?

A

Similar properties of elements occur at regular intervals

42
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

43
Q

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

A

They have the same number of shells

44
Q

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

A

The number of shells increases

45
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

46
Q

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

A

Isotopes

47
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

48
Q

The majority of elements are…?

A

Metals

49
Q

Elements that react to form positive ions are…?

A

Metals

50
Q

Elements that do not form positive ions are…?

A

Non-metals

51
Q

Elements in Group 1 are known as…?

A

The alkali metals

52
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).

53
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.

54
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.

55
Q

How does 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.

56
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
57
Q

State five State Group 7 elements and states of

A

matter of molecules they form
- 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.

58
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
59
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

Cl2 + 2 NaBr → Br2 + 2 NaCl, or
Cl2 + 2Br– → Br2 + 2 Cl–;
in this reaction, an orange colour of Br2 would appear
Cl2 + 2 NaI → I2 + 2 NaCl, or Cl2 + 2I– → I2 + 2 Cl–
Br2 + 2 NaI → I2 + 2 NaBr, or Br2 + 2I– → I2+ 2 Br–;
in these two reactions, a brown colour of I2 would appear

60
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–.

61
Q

Compare group 1 metals with 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

62
Q

State three common characteristics of transition
metals

A
  • Ions with different charges
  • Coloured compounds
  • Catalytic properties
63
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.

64
Q

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

A

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

65
Q

Describe the properties of noble gases. Discuss
the trends in properties 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.

Chemistry (10 decks)

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