Atomic structure and periodic table Flashcards
What is an atom?
The smallest part of an element that makes up all matter
What charges do protons, neutrons and electrons have?
protons= +1
electrons= -1
neutrons= 0
What is another name for the shell?
energy levels
What is an element?
a substance made of only atoms with the same number of protons
What is a diatomic molecule/ element?
An element where atoms form molecules of 2 of the same atom bonded together
Name some examples of diatomic elements
Iodine
Bromine
Chlorine
Fluorine
Oxygen
Nitrogen
Hydrogen
I Bring Clay For Our New House
(all group 7 are diatomic)
Wil changing an atom’s number of proton change the atom?
Yes, protons give atoms it’s identity
What is a compound?
A substance made of at least 2 different elements chemically bonded together
What does the atomic number represent?
Protons (same as electrons)
How do you find out number of neutrons?
Mass number- atomic number
What is the definition of an isotope?
Atoms of the same element with the same number of protons but different numbers of neutrons
What is relative atomic mass?
Average mass of an atom taking into account the different masses of the isotopes
How do you work out relative atomic mass?
sum of (isotope abundance x isotope mass number) / sum of abundance
What did Democritus discover about matter?
All matter were made of small lumps called atoms
What did Dalton discover about the atom?
Atoms were indivisible, miniscule spheres that made up all matter
What did Thomson discover about the atom
Discovered electrons. Created plum pudding model. Electrons could be removed.
What was Rutherford’s experiment and what did it prove?
Alpha particles scattering experiment
Fired alpha particles at a sheet of gold foil
Proved:
1) atoms are made of mainly empty space
2) the nucleus has a positive charge
3) nucleus is concentrated at the centre
and around this are the electrons
How did Dmitri Mendeleev improv ethe periodic table?
Left gaps for undiscovered elements.
Mostly put elements in order of relative atomic mass but switched some around.
These allowed for elements with similar properties to line up in columns.
Do metals form positive or negative ions? What about non-metals?
metals= positive
non-metals= negative
How was the periodic table arranged before Mendeleev?
In order of relative atomic mass
What does the group number show?
number of electrons in outer shell
What does the period number show?
number of energy levels (shells)
Describe trends in melting and boiling points of group 1?
As you go down group one, melting and boiling point decreases
Describe trends in reactivity of group 1?
As you go down group 1, reactivity increases
What does an alkali+ water produce?
metal hydroxide+ hydrogen
Describe trends in melting and boiling point of group 7?
As you go down group one, melting and boiling point increases
Describe trends in reactivity of group 7?
As you go down group 7, reactivity decreases
Describe trends in relative atomic mass of group 7?
As you go down group 7, RAM increases
Describe trends in relative atomic mass of group 1?
As you go down group 1, RAM increases
Describe trends in boiling point of group 0?
As you go down group 0, boiling point increases
How reactive are noble gasses?
Inert/ unreactive because they have a full outer shell
What are ions?
A charged atom or [article, formed through the loss or gain of an electron
Describe properties of transition metals.
. Many typical metal properties
. Form coloured compunds
. Form ions with different charges
What is a catalyst?
Speeds up a reactions without being used up
What is a cation and anion?
cation= positive ion
anion= negative ion
What is ionic bonding?
The electrostatic force of attraction between positively and negatively charged ions
What is ionic bonding between?
metal and non- metal
What charge ions do group 1, group 2, group 7 form?
group 1= +1
group 2= +2
group 7= -1
How are ions in ionic compounds arranged?
In a lattice
Around how many elements are there?
100
(118)
What is a mixture?
Consists of two or more elements or compounds not
chemically combined together. The chemical properties of each
substance in the mixture are unchanged.
Which ways can mixtures be separated?
What type of process are these?
.Filtration
.Simple distillation
.Evaporation and crystallisation
.Fractional distillation
.Chromatorgrpahy
Physical processes
Explain the method of filtration
1)Put filter paper into a filter funnel
2)Pour mixture containing insoluble solid
3) liquid passes through into conical flask but solid won’t
When would you use filtration?
When you want to sperate an insoluble solid from a liquid
When would you use simple distillation? Give an example including how it would work
When you want to separate a liquid from a solution.
e.g. water from salty water because the water evaporates from the solution
. The salt does not evaporate and so it stays behind
Explain the method of simple distillation for water from salty water
- Solution is heated
- The water vapour cools in the condenser and drips into a beaker
- The water has condensed and is now in the beaker, the salt stays behind
What did James Chadwick discover?
Found evidence for the existence of particles in the nucleus with mass but no charge. These particles are called neutron
Explain the method of evaporation and crystallisation.
1) slowly heat solution to evaporate to a smaller volume
2)solution will be more concentrated and will be left be left to cool
3)as solution cools, crystals form and can be obtained by filtration
When do you use fractional distillation?
to separate different liquids from a mixture of liquids
Explain the method of fractional distillation
1)Place mixture in a flask
2)Stick a fractional column on top then heat it
3) Different liquids have different boiling points
4)The liquid with the lowest boiling point will evaporate first. When liquids boiling point (measured by thermometer) matches boiling point it will reach top of column.
5) Other liquids might start evaporating but column is cooler at top so will condense and drip back down
6) When first liquid has been collected raise temperature until the next one reaches the top.
Explain the method of paper chromatography
- Ink or plant dye is dotted along the pencil line.
- Paper is lowered into the solvent in a container (water or ethanol for those that don’t dissolve in water),
3) Put the lid on to stop solvent evaporating
4) Some of the dye seeps up the paper
5) Each different dye in the ink have different solubilities so will travel up at different rates. Some won’t be soluble so will stay on the baseline
6) When solvent has nearly reach the top of the paper, take it out to dry.
Different substances have different solubilities so will travel at different rates, causing the substances to spread apart.
Explain the two phases of chromatography
1)The stationary phase which in paper chromatography is very uniform, absorbent paper
the
2)mobile phase
is the solvent
that moves through the paper, carrying different substances with it
What did Bohr discover?
Electrons orbit the nucleus in shells. The shells are at fixed distances from the nucleus
Where is most of the mass in an atom?
nucleus
How big is the radius of an atom?
0.1 x10nm (x10^-10m)
How big is the radius of the nucleus?
0.1 x 10^-14m
True or false:
All elements in group 0 have 8 electrons in their outer shell
False
Most do but not all
Why do alkali metals get more reactive as you go down?
As you go down period 1, the shells increase so the outer shell electrons are further away from the positive charge it is attracted to in the nucleus. Therefore, it is held on more weakly and can be transferred easier.
What observations will you see when alkalis react with water?
bubbling, flames
When would crystallisation be used instead of evaporation?
When soluble solid decomposes when heated.
Describe the method to separate rock salt.
Filtration and evaporation.
1) Grind mixture so that salt crystals will dissolve easily
2) Put mixture and water and stir. Salt will dissolve. Sand won’t
3 )Filter the mixture and collect the sand.
4) Evaporate the mixture so that salt forms salt crystals.
What’s the problem with simple distillation?
The things you are separating need to have very different boiling points.
True or false: transition metals often make good catalysts.
True
Compare group 1 metals to transition metals.
Group 1 metals are less strong, dense and hard- lower density.
Group 1 metals are more reactive.
What do group 1 metals reacted with water produce?
Group 1 metal+ water -> metal hydroxide+ water
What colour and state of matter is:
Fluorine
Chlorine
Bromine
Iodine
Fluorine- yellow gas
Chlorine- green gas
Red- brown liquid
Iodine- dark grey or a purple vapour
What colour and state of matter is group 0?
Colourless gas
