early earth, groups, metals Flashcards
What is an ionic lattice?
an ion surrounded by other ions with opposite charges because of attraction. They have strong forces of attraction
Lattices have strong forces of reaction meaning lots of energy is needed to…
they have high melting and bp due to sefc
weaken (melting point) or overcome (boiling point) them.
2 ways to conduct an ionic solid.
Melt using a bunsen burner or dissolve it in water
For a substance to conduct by electricity it needs 2 things:
- To have a charge
- To be able to flow/ move
Metals atoms…
loose electrons to become positively charged cations
non-metal atoms…
gain electrons to become negatively charged anions
What do we know about an element if it ends in ide or ate
ide = it contains 2 elements
ate = it contains 3 or more
Covelent bonds happen between what atoms?
2 non-metal
Allotrope?
Elements with different structural forms.
Why can graphite conduct electricity?
Contains a delocalised 4th electron which is moving around freely.
What is the ionic charge of Mg?
2+
what holds ions together in an ionic bond?
electrostatic forces
describe the bonding of a metal
positive cations surrounded by a sea of delocalised electrons
describe some properties of metals
-strong forces of electrostatic attraction
-generally shiny at room temperature
-contains delocalised electrons allowing it to conduct electricity
-layers of atoms can slide over each other making it malleable
Why does the reactivity in group 1 increase as you go down the group?
because the force of attraction between the positive nucleus and negative outer electron decrease as they become further apart making it easier to remove the outer electron.
give 3 properties of a group 7 element.
diatomic molecules
toxic and corrosive
poor conductors of heat and electricity
How do you test for the presence of chlorine
if damp blue litmus paper is placed in chlorine it first turns red then bleaches white.
What is oxidation and reduction?
oxidation - loss of electrons
reduction - gain of electrons
What happens in all radox reactions?
loss and gains of electrons
What is a rate of reaction?
How long it takes reactants to form into products.
What is activation energy?
Endothermic change
Exothermic change
- The minimum amount of energy needed for a reaction to occur.
- Endothermic reaction is when energy is transferred from surroundings to stores of energy in chemical bons (take in)
- Exothermic reaction when energy is transferred from stores of energy in chemical bonds to the surrounding (release)
List collision theory.
- Concentration- increase in concentration means more collisions
- Temperature - The higher the temp the particles speed up and have more energy therefore more collisions.
- Surface area - The increase of surface area means There’s more surface for the reactions to occur
What are catalysts?
They are used to speed up the rates of reactions without being changed themselves or altering the products of the reaction.
How does the addition of a catalyst speed up the rate of reaction?
By lowering the activation energies required for the reaction to occur.
less energy is needed for reac to occ, so more reactant molecules have enough energy & create more succesfful collisions
How are enzymes used within alcoholic drinks?
Alcoholic drinks are produced using an enzyme in yeast. This enzyme catalyses the reaction in which glucose is converted into ethanol (alcohol) and carbon dioxide.
The temp increases in a..
The temp decreases in a..
exothermic reaction
endothermic
Breaking bonds requires energy so its…
Making bonds release energy so its…
Endothermic (+)
Exothermic (-)
define -
- finite resources
- natural gases
3.non-renewable
- resources not being made anymore or take extremely long to form
- mixture of hydrocarbons in a gas state
- being used up faster than they’re being formed and will run out
define
- crude oil -
- hydrocarbons -
6.petrochemicals-
- a complex mixture of hydrocarbons
- compounds containing carbon and hydrogen atoms only.
- substances made from crude oil.
state 2 uses of crude oil.
- fuels for vehicles
- feedstock for petrochemical industry
state the uses for:
gases, petrol, kerosene, diesel oil, fuel oil and bitumen
cooking, cars, aircrafts, trains, ships, surfacing roads.
what is the homologous series?
a series of compounds which contain:
-similar chemical properties
-same general formulas
-gradual variation in physical properties
what is complete and incomplete combustion?
complete - occurs when there’s a plentiful supply of oxygen or air
incomplete - occurs when there’s a limited supply of oxygen or air.
what occurs during both types of combustion?
complete - only co2 and h2o are produced.
incomplete - carbon monoxide and carbon are produced.
why can incomplete combustion produce carbon and carbon monoxide?
there is a limited supply of oxygen so the carbon isn’t oxidised.
what is cracking?
breaking down of larger saturated hydrocarbon molecules into smaller more useful ones.
why are volcanoes thought to contribute to early atmosphere?
bc they release gases such as co2 and water vapour and there was a lot of volcanic activity on early earth.
how do scientists think earths oceans formed?
volcanoes release water vapour and 4 billion years ago earth cooled down, causing water vapour in atmosphere condense into liquid water.
name 3 ways co2 levels have decreased since early earth.
- co2 dissolved in oceans
- sea creatures used dissolved co2 to form shells made of calcium carbonate allowing more c02 to dissolve in oceans
- plants photosynthesising as they took in co2 and released oxygen
chemical test for oxygen.
use a glowing splint, in the test for oxygen the splint re lights.
stromatolites…
bacteria growing in huge colonies and produce sticky mucus which traps sand grains and other sediments, these organisms need to move above the sediment layer in order to get sunlight for photosynthesis.
3 methods that produce methane?
- livestock farming
- rice paddy
- landfill sites
why is carbon monoxide poisonous?
it combines with haemoglobin in red blood cells preventing oxygen combining and reduces the amount of oxygen carried around in the blood stream.
what is an alkane and alkene?
alkane - saturated and joined by single bonds
alkene - unsaturated and joined by carbon carbon double bonds
greenhouse gases -
global warming -
climate changes-
gases in atmosphere that help trap heat (co2 , water vapour, methane)
increase in earths temp
changes that occur when earths temp increases
correlation between fossil fuels and earths surface temp…
more and more fossil fuels are burnt which releases co2 . as co2 levels have increased so has earths av temp.
list 3 negative effects of climate change.
rising sea levels
extreme weather events
lowered ph of oceans (co2 will be released and the acidic gas will be dissolved in seawater)
list ways to limit climate change -
use renewable energy sources, reflect sunlight back into space using giant mirrors, build flood defences in local areas.
evidence that shows little oxygen in earths early atmosphere?
presence of iron pyrite in early rocks as it breaks down in the presence of oxygen.
2 ways acid rain is formed?
- hydrocarbon fuels containing sulfur when burnt, react with oxygen, to create sulfur dioxide gas which dissolves in water in the clouds to form a mixture of acids and fall as acid rain.
- car engines, nitrogen reacts with o2 and creates oxides of nitrogen which dissolves in water in clouds and forms dilute nitric acid.
list properties of groups 0.1.
0 - colourless , low melting and boiling points, poor conduc of h & e
1 - highly reactive as go down, sofft, easily cut,
why do group 7 elements get less reactive as you go down.
outer elec gets further from nucleus and ions are less readily formed
catalysts reduce costs in industrial processes…
by allowing reactions to occur at lower temps which saves costs.
give the changes in heat energy that accompany the
following changes :
a salts dissolving in water
b neutralisation reactions
c displacement reactions
d precipitation reactions
a. both dep on salt
b. exothermic
c. exothermic
d. both
when alkali metals react with water what are the products?
a metal hydroxide and hydrogen
