c1 atomic structure and the periodic table Flashcards
define atom
the smallest part of an element that can exist
what are the groups on the periodic table
vertical, 1-7 then 0
what are periods on the periodic table
horizontal
how to separate a mixture
physical processes:
filtration - insoluble solid from liquid
crystallisation - soluble solid from solution
distillation - liquid from a solution
fractional distillation - liquid from mixture of liquids
chomatography - mixture of dyes
which elements exist as molecules made up of two of the same atoms joined together
iodine, bromine, chlorine, fluorine, oxygen, nitrogen, hydrogen
how do you remember the elements that are written as (element)2
I Bring Clay For Our New House
define compound
a substance that contains two or more elements that are chemically combined in fixed proportions
what does it mean if the second word of a compounds name starts with mon, di or tri
its made up of non metals only, and shows how many there are of that element for every one atom of the first element. e. g carbon dioxide, one carbon to two oxygen (C02)
what is an ion
and charged particle formed when an atom or a group of atoms loses or gains an electron
how does simple distillation work
- solution placed in flask and heated by bunse burner
- liquid evaporates, vapour passes through glass tube which has thermometer attached
- tube surrounded by condenser, with cold tap water continuously running through to cool the vapour
- vapour passes through and condenses
- liquid formed (pure distilled water) collected in beaker
how does fractional distillation work
- solution of multiple boiling points placed in flask and heated
- liquids evaporate, mixture of vapour passes through fractionating column, which contains hundred of glass beads
- liquid with lower BP evaporates more easily. liquid with higher BP condenses in glass beads and drip back into flask, as tube is cooler nearer top
- when thermometer reads lowest BP, that liquid has reached the top and can condense in condenser and be collected
- flask continues to heat, so next liquid can be collected
what is a reactant
The substances that react together in a chemical reaction
what is an aqueous solution
forms when a substance dissolves in water
What is the law of conservation of mass?
total mass of the product is equal to the total mass of the reactants
- no atoms lost or gained
What is a plum pudding model?
A ball of positive charge with negative electrons studded into it
how were elements originally arranged, and why was this inaccurate
- in triads of similar chemical properties
- atomic weight, as every 8th element reacts similarly
however, protons were not discovered so atomic weight could be affected by isotopes, meaning sometimes elements with different properties were grouped
how did mendeleev develop the first periodic table
- ordered elements by atomic weight, but swapped some to fit the physical and chemical patterns of other elements within group
- left gaps in periodic table for undiscovered elements, predicting properties
Why was mendeleevs table accepted
as elements were discovered, they fit the patterns in the gaps left by mendeleev
how has the periodic table changed since mendeleev
- protons discovered, so elements arranged by atomic number rather than weight. this puts them in correct order as the presence of isotopes affects atomic weight
- group 0 added
what is the relative atomic masses of the subatomic particles
protons and neutrons: 1
electrons: 0
what are the charges of the subatomic particles
protons: positive
neutrons: neutral
electrons: negative
what is an isotope
different forms of the same element that have the same number of protons but a different number of neutrons
what does abundance mean
how common or rare that isotope is
what is the equation for relative atomic mass
sum of (isotope abundance x isotope mass)
————————
100
define molecule
2 or more atoms held together by chemical bonds
how do you find percentage mass of an element
mass of element
————————- x 100
total mass of compound
What is paper chromatography?
A process used to separate mixtures of soluble substances
how does chromatography work
The solvent dissolves the different substances in the mixture and carries them up the paper
each are attracted to the two phases in different proportions, meaning they spend different amounts of time in each
This causes pure substances to form one spot and impure to form multiple
what are the two phases in chromatography?
The stationary phase and the mobile phase
how can you tell if two substances are the same on a paper chromatogram
- same spots of same colours
- same distance up paper
whose had the first ideas about atoms and what were these ideas
John Dalton- all matter was made a tiny particles called atoms, which he imagined as tiny spheres that couldnt be divided
what did jj thompson do
JJ Thompson - discovered atoms contain negatively charged paarticles, electrons.
designed plum pudding model
how was the plum pudding model tested and who did it
Ernest Rutherford - rutherford scattering experiment
positively charged alpha particles were fired at thin gold foil. Most of the particles went through the foil,
showing that the gold atoms were mostly empty Space
a few were scattered in different directions or bounced back, showing that mass of atoms is concentrated in the centre, positively charged
What did Ernest create?
A new model called the nuclear model.
the mass of an atom is concentrated at its centre, the nucleus.
And the nuclues positively charged
who adapted the nuclear model and what did he discover
niels bohr, discovered that electrons orbit the nucleus at fixed distances, known as energy levels
what was dicovered after niels
the nucleus contain small particles called protons, which each had a small amount of positive charge.
Who discovered neutrons?
James Chadwick
how to identify group of element from structure diagram
number of electrons in outer shell
radius of an atom vs radius of nucleus
1x10^-10m (0.1nm)
1x10^-14
atom is over 10 000 x bigger than nucleus
what are groups arranged in?
Elements with similar properties
what happens when metals reaxt
they form positive ions, as they lose electrons to get a full outer energy level (become stable
properties of metal
conductor
shiny
high-density
malleable
ductile
high BP and MP
properties of nonmetals when solid
Poor conductor
dull
low-density
brittle
low BP and MP
What are elements in group 0 called and what are some properties
Noble gases
- unreactive
- BP lower that room temp
why are noble gases unreactive
outer shells are full, atoms are stable
How did the elements change as you go down group 0
- boiling point increase as there are more intermolecular forces as atoms become larger (more energy needed)
what are group 1 elements called?
Alkali metals
Properties of alkali metals
soft
relatively low melting points
low density
highly reactive
form 1+ ions
properties of transition elements
hard and strong
high melting point
high density
low reactivity
form ions with different charges
form coloured compounds
used as catalysts
how do group 1 metals react with oxygen
react rapidly to form metal oxide
- 2 alkali metals lose one outer electron to oxygen, eg lithium forms Li2o
how do group 1 metals react with chlorine
react rapidly to form metal chloride
- alkai metal lose one outer electron to chlorine, eg lithium becomes LiCl
how do group 1 metals react with water
reacts to form metal hydroxide and hydrogen
- effervescence of fizzing, meaning gas (hydrogen) produced
- universal indicator changes colour, meaning alkaline solution (metal hydroxide) produced
eg lithium becomes LiOH + H2
how do the different group 1 metals react to being placed in water, eg potassium
they will react faster and give out more energy as you go down
- potassium releases enough energy to ignite hydrogen
what happens to elements as they go down group one?
- they get more reactive. as you go down group, atom becomes larger, meaning negative outer electron becomes further from positive nucleus, so are lost more easily. electrons also repel outer electrons
- lower MP and BP
What is group 7 called
Halogens
how are group 7 atoms found
as molecules, two atoms joined by covalent bond
What happened to elements as you go down group 7
- less reactive. atom becomes larger, meaning outser shell becomes further. this makes it hader to gain extra electron as there is a weaker attraction to positive nucleus. electrons also repel outer electrons
- less likely to displace other halogens
- MP and BP increase
- molecules become larger
how do group 7 elements react with non metals
covalent bonding
they will share outer electron to form molecular compound
how do group 7 elements react with metals
ionic bonding to form metal-ide, eg fluorine becomes fluoride
they will gain electron from metal to become 1- ions
describe how displacement reactions can occur with group 7 elements
- more reactive halogen displaces less reactive halogen in aqueous solution of its salt
eg sodium bromide + fluorine:
fluorine is more reactive than bromine, so:
sodium fluoride + bromine
what is a mixture and what properties will it have
when different elements or compounds are not chemically combined
same properties as different components
how to use display on periodic table to get information about the atomic structure of ions
top number: mass number - number of protons and neutrons
bottom number: atomic number -number of protons
if 1+ charged: ion has 1 fewer electrons than protons
if 1- charged: ion has 1 more electrons than protons
how to use display on periodic table to get information about the atomic structure
top number: mass number - number of protons and neutrons
bottom number: atomic number -number of protons (and electrons)
