Issy 3rd Form Chemistry Flashcards
Atoms are?
Everything in the universe is made of tiny particles. We call these particles ‘atoms’.
Elements are
Substances which contain only one type of atom
eg gold, tin and carbon
All of the atoms in an element have the same mass and the same properties
Elements can be solid liquid or gas
Compounds are
substances where DIFFERENT atoms are joined together by chemical bonds
eg CO2 or NaCl
A mixture is
a substance where the DIFFERENT atoms are NOT joined together with chemical bonds
eg air which is a mixture of different gases like N2, O2 and CO2
How are the particles organised in solids liquids and gases?
Solid
Particles are arranged in a regular pattern of lines and rows. The particles cannot move away from the position they are locked in, they just vibrate on the spot. The particles are very close together and they always touch.
Liquid
The particles in a liquid can move freely over each other.
The particles are arranged randomly.
Not all of the particles touch, but each particle will be touching at least one other particle.
There are small gaps between particles.
Gas-
The particles move randomly in all directions and travel very fast, zipping around.
The particles do not touch and are very spread out.
Sometimes gas particles bounce off each other (and off the walls of any container) if they happen to collide.
Changes of state- what is boiling?
Boiling is a change from liquid to gas.
Boiling happens when liquid particles are heated, making them move faster and faster.
Eventually, the liquid particles will be moving very quickly and in random directions, without being connected to any other particles – they have changed into the gas particle arrangement.
When you boil the kettle the steam that comes out the top is water vapour (water as a gas), because the liquid water has been heated up enough to boil.
Water boils at 100oC.
Changes of state- what is evaporation?
Evaporation is also a change from liquid to gas.
A liquid boils when every particle has gained enough energy to break free.
what is the difference between evaporation and boiling?
The difference between evaporation and boiling is that evaporation can happen at any temperature.
When you get out the shower, the water on the doors eventually ‘disappears’ because it evaporates.
It doesn’t boil, but it does turn into a gas.
This is because different particles in a liquid have different amounts of energy.
Some particles will gain enough energy to break free and will become a gas.
Changes of state- what is freezing?
Freezing is when a liquid turns into a solid.
E.g. when water freezes to ice, which happens at 0oC.
To freeze a liquid, you have to cool it down, which makes the particles travel slower and slower until they are just vibrating in a fixed position and are all very close together.
The particles will then look like the particle arrangement in a solid and the substance has frozen.
Changes of state- what is condensation?
Condensation is a change of state from a gas to liquid.
Condensation happens when you cool down a gas and reduce the energy of the particles.
The particles slow down and clump together, taking the arrangement of a liquid.
Changes of state- what is melting?
Melting is a change from solid to liquid.
Melting happens when the solid particles get some extra energy, which makes them vibrate faster and faster until they have enough energy to break away from their fixed position.
Then the particles can move freely over each other, and have turned into liquid particles
Heating something will give solid particles enough energy for them to adopt a liquid particle arrangement.
What is density?
Density means how much mass something has in a certain volume.
Put the three states of matter in order from most dense to least dense
Solid
Liquid
Gas
How do gases cause pressure?
Gas particles move quickly in all directions.
They do not travel far before they bump into each other or the walls of their container.
Each time a particle hits the wall of a container, it causes pressure.
The more often gas particles hit the walls of their container, the higher the pressure.
The harder gas particles hit the walls of their container, the higher the pressure.
If the pressure gets too high, the container will burst.
E.g. squashing a balloon raises the pressure and bursts it.
Can liquids cause pressure?
Yes Liquids can cause pressure sometimes. For example, when a water pipe bursts.
Can solids cause pressure?
Solids cannot cause pressure because their particles cannot move off their fixed positions.
What is pressure?
Pressure means how much force is applied to something divided by the area it is applied over.
P=F/A
what are Chemical symbols for elements?
Every element has a symbol, which is shown on the periodic table.
Some symbols are just one letter, some are two. The first letter is always a capital. If there is a second letter, it is always lower case.
E.g.
Hydrogen is ‘H’.
Helium is ‘He’.
Magnesium is ‘Mg’.
Sulfur ‘S’.
Lithium is ‘Li’.
Bonded elements - what are they and can you name them?
Some elements have 2 atoms which are bonded together.
eg the chemical symbol for hydrogen is H but hydrogen gas is a bonded element with another hydrogen atom so is H2 (the 2 should be smaller and sit at the bottom of the line but I can’t do it on this card!)
as well as hydrogen other atoms which travel in pairs are
nitrogen oxygen fluorine chlorine bromine and iodine
What are chemical symbol for compounds?
The formulae for compounds are written by putting the element symbols together in a line with no gaps between them.
Because all compounds are made of elements, this is always the case.
Carbon dioxide compound is made of carbon and oxygen atoms. The formula is CO2. The little numbers tell you how many of each atom is in a compound. The number is shown just after the element. If there is no number given on the right of an element, then there is just one atom of it.
Water is made of hydrogen and oxygen atoms. The formula is H2O.
Any metals usually go first, and any oxygens usually go last.
The formula of magnesium oxide is:
MgO.
MgCl2 is the formula for magnesium chloride, which contains magnesium and chlorine atoms.
The ‘l’ is a lower case 'L', and not a capital ‘I’. So the compound has magnesium and chlorine, not magnesium, carbon and iodine.
The chemical formula for sulfuric acid is H2SO4
What elements make up sulfuric acid and how many of each are there in one molecule of it?
2 x hydrogen
1 x sulfur
4 x oxygen
What is a redox reaction?
A redox reaction has both oxidation and reduction
What is oxidisation?
A loss of electrons
What is reduction?
A gain of electrons
What is a displacement reaction?
Give an example of solids which displace
Give an example of displacement in solution
.A more reactive metal displaces a less reactive metal from a compound.
Aluminium displaces iron from iron oxide giving aluminium oxide + iron.
Copper displaces silver in silver nitrate solution to give , copper nitrate + silver.
Is there conservation of mass during a chemical reaction?
In a chemical reaction, the atoms rearrange and join together in different ways.
As the same number of each type of atom is there at the end as there was at the start, then the mass doesn’t change.
If we think about the total number of each atom, we can see it stays the same.
So the mass will also stay the same – it is conserved.
This is true for any chemical reaction because atoms cannot be created or destroyed.
How do the group 1 metals react with water?
They all react violently fizzing around the top of the water, producing hydrogen and the metal hydroxide. The further down the group the more reactive they are
eg 2Li + 2H20 ——-> 2LiOH + H2
Explain the reactivity of the group 1 metals in terms of electronic configuration
The group 1 metals all have 1 electron in their outer shell, this makes them more reactive than group 2 as they have 2. They are trying to lose the electron in their outer shell to gain a stable electronic structure.
There is an attraction between the nucleus and the electron in the outer shell.
The further away the electron is from the nucleus the less the attraction so the easier it is to lose the electron.
The bigger the atomic mass the more shells there are and so the group 1 metals get more reactive the further down the group you go.
What are the vertical columns of the periodic table called, can you name some of them?
The vertical columns of the periodic table are called groups.
Elements in each group can be named:
Group 1: the alkali metals.
Group 7: the halogens.
Group 0: the noble gases.
Where in the periodic table are the transition metals?
The large block in the middle is called the transition metals.
Name some facts about the groups of the periodic table
Elements in each group have similar properties and patterns to each other. For instance:
Group 1, the alkali metals, are very reactive. They get more reactive as they go down the group. Group 7, the halogens, are also reactive. They get less reactive as they go down the group.
What are the rows of the periodic table called? Do the elements in each row have any patterns? Name 2 patterns.
The horizontal rows of the periodic table are called periods.
Patterns can also be seen as you go along the periods.
The size of the atom decreases as you go from left to right along the period.
The elements get less metallic as you go from left to right.
Explain the reactivity of the group 7 halogens in terms of electronic configuration.
The group 7 halogens all have 7 electron in their outer shell, they are trying to gain an electron in their outer shell to gain a stable electronic structure.
There is an attraction between the nucleus and the electrons in the outer shell.
The further away the electron is from the nucleus the less the attraction so the harder it is to gain the electron. The closer the shells are to the nucleus the more the electron will be attracted.
What is the electronic structure of the noble gases
They all have completed outer shells and so are stable and non reactive
