Chemistry - Atomic structure and the periodic table Flashcards
What are all substances made
from
Atoms
What is an atom
The smallest part of an element that can exist
What is the radius of an atom
0.1 nm (nanometres) (1 x 10-10m), it is very small
What is the radius of the
nucleus
1 x 10-14 m (1/10000th of the radius of an atom)
Where is most of the mass in an
atom located
In the nucleus
What can elements be
represented as
Symbols
How many elements are there
About 100
Where are elements shown
The periodic table
What is a compound
Two or more different types of atoms chemically joined together in fixed proportions
How can compounds be separated into their elements
By chemical reactions
Are the properties of a
compound the same as the
elements they are made from
No
What is a mixture
Two or more different types of elements or compounds not chemically bonded together, the chemical properties of each substance in the mixture are unchanged
5 ways to separate a mixture
Crystilisation, simple distillation, fractional distillation, chromatography and filtration
Why are the techniques used to
separate mixtures described as
physical processes
As mixtures contain two or more elements or compounds not chemically combined
Why is a lid used
chromatography
Stops solvent evaporating
How does filtration work
Pass through filter paper, liquid passes through, insoluble particles get caught by the filter paper
How do you carry out
crystallisation
Evaporation dish and heat source. Filter crystals out of the solution
How can you get sand and salt
from a mixture of the two
Dissolve in water, salt is soluble, sand isn’t. Filter to remove sand, then use crystallisation
What two processes are involved
in distillation
Evaporation and condensation
Where is the hottest part in
fractional distillation
The bottom
What property must the mixture
have to be able to separate by
fractional distillation
Each part of the mixture must have different boiling points
What is an element
A substance made up of only one type of atom
What is a molecule
Two or more atoms joined together e.g. O2, Cl2, H2O, CO2
Where are the reactants found
in an equation
Left side
Where are the products found in
an equation
Right hand side
What is distillation
The separating of a liquid using evaporation and then
condensation
A method used to separate two
or more liquids
Fractional distillation
A method used to separate the
coloured compounds in a
mixture
Chromatography
A method used to separate an insoluble solid from a liquid
Filtration
What is crystallisation
A way to separate a dissolved solid from a solution by evaporation to leave crystals of the solid
Before electrons were
discovered, was it thought that
atoms could be divided
no
Before electrons were
discovered, atoms were thought
to be what
Tiny spheres
What model did the discovery of
the electron lead to
Plum pudding model
What was the plum pudding
model
That the atom was a ball of positive charge with negative
electrons embedded in it
What model replaced the plum
pudding model
Nuclear model
What experiment led to idea
that mass of the atom was
concentrated in the centre
Alpha scattering experiment
What would happen with the
alpha particle experiment if the
plum pudding model was correct
Expect particles to pass straight through or slightly deflected
What was observed in the alpha
scattering experiment
Most of the particles passed through
Some deflected more than expected
Very few deflected backwards
What charge are alpha particles?
Positively charged
Explain the observations of the alpha scattering experiment
Most of the particles passed through = atom is mostly empty space
Some deflected more than expected = alpha particles hit a positively charged centre and repelled
Very few deflected backwards = alpha particles hit a concentrated mass
Describe the nuclear model
has a positively charged nucleus, most of the atom is empty space
What sub atomic particle was
discovered first
Electron
Who led to the idea that
electrons are in orbitals/shells
Niels Bohr
What order where the sub
atomic particles discovered
Electron, proton the neutron
Who provided evidence for the
existence of neutrons within the
nucleus
Chadwick (about 20 years after the nucleus idea was
accepted)
What are the differences
between the plum pudding
model and the nuclear model
Plum - single ball of positive charge spread throughout,
electrons in embedded, no nucleus, no neutrons
nuclear - positive centre/nucleus, electrons in fixed positions, has a nucleus, has neutron
What did Bohr suggest about the arrangement and movement of electrons
Electrons orbit the nucleus in shells that are a fixed distance
from the nucleus. Electrons can only be found in these shells
What particle was discovered as the nucleus was found to be
positive
Proton
Name the three sub atomic particle
Proton, neutron & electron
What is the relative charge of a
proton
1+
What is the relative charge of a
neutron
0
What is the relative charge of an
electron
-1
Why do atoms have no overall
electrical charge (are neutral)
The number of positive proton equals the number of negative electrons so charges cancel out
What does the atomic number
tell you
number of protons
What makes an atom of an
element the element it is
The protons, e.g. If an atom has 8 protons, it must be oxygen
What makes atoms of elements different to each other
different amount of protons
What is the relative mass of a
proton
1
What is the relative mass of a
neutron
1
What is the relative mass of an
electron
Very small
What is mass number
The sum of the protons and neutrons in an atom
What is an isotope?
The same element but with the same number of protons but different numbers of neutrons
Why is the relative atomic mass of chlorine not a whole number
Has more than one isotope
How do the chemical properties of an isotope differ
Doesn’t - has have the same number of electrons
How do you work out the number of protons
Use the atomic (proton) number
How do you work out the number of electrons in an atom
Same as the protons
How do you work out the number of neutrons
Mass number - atomic number
What is relative atomic mass
The average value that takes account of the abundance of the isotopes of an element
What do the electrons occupy in
an atom
lowest energy available
How many electrons are there found in shells 1, 2 & 3
2,8,8
What sub atomic particle is involved in bonding (chemical
reactions)
electrons
What holds atoms of elements
together in compounds
Chemical bonds
What holds atoms of elements
together in compounds
Chemical bonds
How were early periodic tables
arranged (Newland and Mendeleev)
By atomic weights (as protons, neutron and electrons were not discovered)
What did Newland do wrong
Put more than one element in a box
Followed a strict order of atomic weight
His pattern eventually broke down
He didn’t leave any gaps for undiscovered elements which led to elements being place in inappropriate groups
What is the name of the
scientist who first published the periodic table
Dmitri Mendeleev
What did Mendeleev do to solve
the problem of elements not in the correct groups
He left gaps for undiscovered elements
He was able to predict the properties of these AND was
correct
How is the modern periodic
table ordered?
In order of atomic number (protons)
What are elements with similar
properties place in
Groups (columns)
What do all elements in the
same group have in common?
The same number of electrons in their outer shell
How is the modern periodic
table arranged
Atomic number (protons) with elements in the same group as their outer number of electrons
What is the name given to the
columns on the periodic table
Group
rows of the periodic table
Periods
What does the group number of
an element tell you
The number of electron in its outer shell/ energy level
What does the period number of an element tell you
Number of energy levels the atom has
How many groups are there on the periodic table
8
How are the metals and non-metals arranged in the periodic table
Metals are on the left hand side and metals on the right
What is an ion
A charged particle
What types of ions do metals
form
Positive, as they lose electrons to get a full outer shell
What types of ions do non-
metals form
Negative, as they gain electrons to get a full outer shell
What elements are founds in the
block of the periodic table
between groups 2&3
Transition metals
What are the elements in group
0 called
Noble gases
Why are Noble gases unreactive/inert
As they have a full outer shell so their atoms have stable
electron arrangements (He-2, all others-8)
What happens to the boiling
point of the Noble gases as you
go down the group
Increases, as relative atomic mass increases so stronger
intermolecular forces
What does monoatomic mean
Noble gases
Exist as atoms
What are the elements in group
1 called
Alkali metals
How many electrons do all group 1 elements have in their outer
shell
1
Why do the metals in group 1
have similar properties
All have 1 electron in their outer shell
What happens to the melting
point as you down group 1
Decreases
Due to metallic bonds becoming weaker as go down the group
What happens to the reactivity
of the group 1 metals as you go
down the group
Increases
Why do the alkali metals
become more reactive as you go
down the group
Increase in number of electrons/electron shells,
outer electron is further from the nucleus
so is less attracted to the positive nucleus
so easier to lose an electron
Give three characteristics of
alkali metals
Metals, soft, highly reactive
What are the products when a
group 1 metals reacts with
water
Metal hydroxide and hydrogen
What is the word equation for
the reaction of sodium with
water
Sodium + water sodium hydroxide + hydrogen
What is the balanced symbol equation of sodium with water
2Na + 2H2O —> 2NaOH + H2
What observations do you see
when an alkali metal reacts with
water?
Alkali metals float on water = less dense than water
alkali metals fizz = hydrogen gas released
universal indicator (if added) goes purple = alkali produced aka metal hydroxide
metal dissolves = metal reacting to produce metal hydroxide (aq)
Reactions become more vigorous as go down group 1
What is observed when lithium
reacts with water
Floats, moves on the surface, fizzes
What is observed when sodium
reacts with water
Floats, forms a ball, moves on the surface, fizzes, can see a yellow flame
What is observed when
potassium reacts with water
Floats, forms a ball, moves on the surface, fizzes, a lilac
flame
What is formed when alkali
metals react with oxygen
Metal oxide
What is the word equation for
the reaction of sodium with
oxygen
Sodium + oxygen sodium oxide
What is the symbol equation for the reaction of sodium with oxygen
4Na + O2 —> 2Na2O
What observations do you see
when lithium reacts with
oxygen?
Red-tinged flame
Bright flame in oxygen
White solid formed
What observations do you see
when sodium reacts with
oxygen?
Yellow-orange flame
Brighter flame in oxygen
White solid formed
What observations do you see
when potassium reacts with
oxygen?
Lilac flame
Even brighter flame in oxygen
White solid formed
What is formed when alkali
metals react with chlorine
A metal halide is formed e.g. Sodium chloride
What is the word equations for
the reaction of sodium with
chlorine
Sodium + chlorine sodium chloride
What is the symbol equation for
the reaction of sodium with
chlorine
2Na + Cl2 2NaCl
What observations do you see
when group 1 elements react
with chlorine?
Bright flame
White solid
What are the elements in group
7 called
Halogens
How many electrons do all
groups 7 elements have on their
outer shell
7
What state is chlorine at room
temperature and its colour?
Yellow/ green gas
What state is bromine at room
temperature and its colour?
Brown liquid
What state is iodine at room
temperature and its colour?
Purple solid
Three properties of the halogens are
Non-metals,
very reactive,
diatomic (exist as molecules),
melting points and boing points increase down the group
(links with change of states as go down the group)
What is the charge on a halide
ion
-1, as lose one electron to get a full outer shell
What happens to the reactivity
of the group 7 halogens as you
go down the group
Decreases
Why do the halogens become
less reactive as you go down the
group
Increase in number of energy levels,
outer shell of electrons are further from the nucleus
so less attraction between outer electrons and nucleus
so harder to gain and attract a new electron
What sort of compounds do
halogens form with other non
metals
Covalent
What sort of compounds do
halogens form with metals
Ionic
What sort of molecules do all
halogen form
Diatomic, go round in pairs
What is a displacement reaction
When a more reactive element displaces (kicks out) a less reactive element, so more reactive halogen (higher up the group) can kick out a less reactive halogen from an aqueous solution of its salt
A word equation to show the
displacement reaction between
chlorine and sodium bromide
Chlorine + sodium bromide bromine + sodium chloride
A symbol equation to show the
displacement reaction between
chlorine and sodium bromide
Cl2 + 2NaBr Br2 + 2NaCl
where are the transition metals found in the periodic table
in the centre, between groups 2 and 3
Compare properties of transition metals to alkali
higher melting point,
higher density,
stronger,
harder
how does the reactivity of the transition metals compare to the reactivity of alkali metals
less reactive
what are the properties of transition metals
can form different charged ions
form coloured compounds
useful as catalysts
what property of transition metals is an important industrial use
used as catalysts to speed up reactions
