Chemistry Paper 1 Flashcards
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What is an element?
A substance made up from only 1 type of atom
What is an atom?
the smallest part of an element that can exist
Total mass of products in a reaction =
Total mass of reactants
Why does total mass of products = total mass of reactants?
No atoms are lost or made
4 main separation techniques?
Filtration
Distillation (Simple//fractional)
Chromatography
Crystallisation
Who discovered the electron?
JJ Thomson
What did Thomson believe atoms contained? What was this model called?
negative electrons surrounded by a sea of positive charge. plum pudding model
What did Geiger and Marden do? What did this show Rutherford?
bombarded a thin sheet of gold foil with aloha particles»_space; some bounced back/ were deflected»_space; showed Rutherford that the positive charge in an atom must be concentrated in a very small area.
Who discovered the neutron?
James Chadwick
What did Bohr do?
Deduced that electrons must orbit the nucleus at a specific distance (otherwise they would spiral inwards)
Atomic radius of atoms?
0.1nm // 1x10^-10
what is the atomic number?
number of protons
what is the mass number?
number of nucleons (protons+neutrons)
How are element arrange in the modern periodic table/
In order of increasing mass number
What is an isotope?
An element with a different number of neutrons
what is an ion?
an atom that has lost or gained an electron
how did John Newlands order the periodic table?
KNOWN elements in order of atomic weight»_space; notices patterns, but missing elements caused problems
What did Dimitri Mendeleev realise?
That some elements were yet to be discovered
what did Dimitri Mendeleev do?
LEFT GAPS for elements that were yet to be discovered
When subatomic particles were discovered, what was it revealed that Mendeleev had done?
Ordered them in increasing number of protons (atomic number)
What are group 0 elements called?
Noble Gases
What are group 1 elements called?
Alkali metals
What are group 7 elements called?
Halogens
Noble Gases…
Full outer shell
Very stable and unreactive
Boiling points INCREASE as you go down group
Alkali Metals…
1 electron in outer shell
LOW melting and boiling points»_space; DECREASE as you go down
Become MORE reactive as you go down
Why do alkali metals become more reactive as you go down?
Outer electron gets further away from influence of nucleus, so it can be lost more easily
What are alkali metals stored under? Why?
Oil»_space; react vigorously with oxygen and water (even moisture in air)
When alkali metals react with water, what is given off and what is formed?
Hydrogen gas given off, a metal hydroxide formed
Group 1 - low or high density?
Low
Alkali metals react with non metals to form…
Ionic compounds
When a metal hydroxide is dissolved in water, what is produced?
an alkaline solution
Halogens…
7 electrons in outer shell
Pairs of atoms
Reactivity decreases down the group
Boiling and melting point INCREASE as you go down
Why do halogens become less reactive as you go down?
Outer shell get further away from the influence of the nucleus, so it is less easy to gain an electron
Halogens react with metals to produce….
ionic salts
A more reactive halogen will displace a less reactive halogen…
From an aqueous solution of its salts
What do transition metals form?
Coloured compunds
Transition metals have ions…
With different charges eg - Fe2+ & Fe3+
What can transition metals be used as?
Ctatalysts
Properties of Transition metals
Good conductors of heat
Good conductors of electricity
Can easily be bent or hammered into shape
What kind of force of attraction between IONIC COMPOUNDS?
STRONG ELECTROSTATIC FORCES
Ionic bonding includes..
A metal and a non-metal
Properties of ionic compounds?
STRONG ELECTROSTATIC FORCES
HIGH melting and boiling points
DO NOT conduct electricity when solid»_space; ions cannot move
DO conduct electricity when MOLTEN»_space; charges ions are free to move about and carry their charge
What is a metallic bond?
The attraction between positive ions and delocalised electrons
Why are metals good conductors?
They have FREE DELOCALISED ELECTRONS which are FREE TO CARRY THEIR CHARGE
Uses and properties of aluminium
High voltage power cables, furniture, drinks cans, foil food wrap
Corrosion resistant, DUCTILE, MALLEABLE, good conductivity, low density
Uses and properties of Copper
wires, water pipes, cooking equipment
DUCTILE, MALLEABLE, good conductivity
Uses and properties of gold
jewellery, electrical junctions
DUCTILE, shiny, good conductivity
What does malleable mean
can be easily bent or hammered into shape
What does ductile mean?
can be easily bent or hammered into shape
Covalent bond occurs between…
2 non metals
What is a covalent bond
a shared pair of electrons between atoms
A property of covalent bonds
very strong
