C1: Atomic Structure and the Periodic Table Flashcards
What is an atom?
The smallest part of an element that can exist.
What is an element?
A substance that can’t be broken down and only contains one type of atom.
What is a compound?
A substance that contains at least two different elements, chemically combined in fixed proportions.
What is an isotope?
An element with the same number of protons but a different number of neutrons
What are the naming compounds rules?
- The metal goes first
- When two elements combine then it will usually end in ‘-ide’
- When three elements combine and one is oxygen it usually ends in ‘-ate’
- If a compound contains
-OH it’s a hydroxide
What is the compound made from magnesium and iodine?
Magnesium iodide
What compound is made up of magnesium, carbon and oxygen?
Magnesium carbonate
What is a chemical reaction?
A change to the arrangement of atoms and the molecular structure of reactants, to form products.
What is on the left side of a word equation?
Reactants
What is on the right side of a word equation?
Products
What is a mixture?
A substance that contains more than one atoms that are not chemically bonded.
What is easier to separate a compound or a mixture?
Mixture
How does filtration work?
Allows small molecules through but not big molecules.
How does evaporation work?
When the liquid evaporates leaving the solid.
Are there any changes in properties when a mixture is made?
They keep the same properties as they did as elements.
Are there any changes in properties when a compound is made?
Their properties change- appearance, and magnetic.
What types of process are mixtures separated by?
Physical processes
What are some physical processes that separate mixtures?
. filtration
. evaporation/ crystallization
. distillation
. chromatography
How do you choose what technique to use when separating mixtures?
. boiling point
. solubility
. magnetic or not?
What does soluble mean?
A substance that can dissolve to become a solution.
What does insoluble mean?
A substance that can’t dissolve to become a solution.
What is a solute?
A solid that dissolves in a solvent to produce a solution.
What is a solvent?
A substance (usually liquid) that a solute can dissolve in to become a solution
What is a solution?
The product of a solute dissolving in a solvent.
How would you carry out a filtration method?
- Put the mixture into a beaker and add 50 ml of warm water.
- Fold the filter paper and the place in the funnel on a conical flask.
- Place the filter paper in a filter funnel and pour the mixture of salt, sand and water onto the paper.
- Pour the filtrate into an evaporating basin and place on a tripod and gauze over a bunsen burner.
- Heat slowly until crystals start to form around the edge of the solution.
- Place the filter paper containing the residue and the evaporating basin with salt crystals in a drying oven.
What is chromatography?
The separation of inks and other soluble substances based on their solubility.
How would you carry out a chromatography practical?
- Draw a baseline at the bottom of your chromatography paper with a pencil.
- Draw a dot of ink on the pencil baseline.
- Pour around 1cm of solvent into the chromatography tank.
- Place filter paper in the solvent so the baseline is above the solvent line.
- Use a lid on the tank until after the experiment is finished. Let the solvent run up the paper until the solvent front goes near the top of the filter paper.
- Draw a line to mark the top of the solvent line.
- Leave the paper to dry.
Why does the baseline need to be drawn in pencil?
The pen would smudge
Why should the sample not touch the water?
It will dissolve in the water.
What would you see if it was a pure colour?
Just one spot of dye above the dye that was on the baseline.
What would happen if the dye was more soluble?
It will travel further up the filter paper.
What would happen if the dye was less soluble?
Won’t travel as far up the paper.
What would happen if the dye was insoluble?
Won’t travel up the paper.
What are the two phases of chromatography?
The stationary phase and the mobile phase
What is the stationary phase in chromatography?
The paper
What is the mobile phase in chromatography?
The solvent that moves up the paper carrying the different substances
What the name of a liquid that filters into a conical flask?
Filtrate
Why does an increase in temperature mean a liquid can change into a solid?
Energy is required for the particles in a liquid to overcome the forces of attraction.
What does saturation means?
The point when no more solute can dissolve
What technique separates insoluble solids from liquids?
Filtration
How do you filter something to get a insoluble solid from a liquid?
- Fold filter paper into a cone shape and put in a funnel
- Pure in the liquid and wait for the liquid to filter through the paper
- The insoluble will stay in the filter paper as it is too big to go through the filter paper.
What are 2 ways to separate soluble solids form liquids?
- evaporation
- crystallization
What is the method for evaporation?
- pour the solution into an evaporating dish
- slowly heat the solution. the solvent will evaporate and the solution will get more concentrated. eventually crystals will evaporate
- keep heating the evaporating dish until all you have left are dry crystals
What is the method for crystallization?
- pour the solution into an evaporating dish and gentle heat the solution.
- one some of the solvent has evaporated or when you see crystals start to form, remove the dish from the heat and leave the solution to cool.
- the salt should start to form crystals as it becomes insoluble in the cold, highly concentrated solution
- filter the crystals out of the solution, and leave them to dry
What is the difference between fractional and simple distillation?
Fractional separates a mixture of liquids whereas simple is used to separate solutions.
What is the method for simple distillation?
- the solution is heated and the part of the solution that has the lowest boiling point will boil first.
- the vapor then cools and condenses and is collected
- the rest of the solution is left behind in the flask
What is the method for fractional distillation?
- put the mixture in a flask and stick a fractionating column at the top and heat it
- the different liquids have different boiling points so they will evaporate at different temperatures
- the liquid with the lowest boiling point evaporates first when the temperature on the thermometer reaches the boiling point it will reach the top of the collum
- liquids with higher boiling points might also start to evaporate but the column is colder as it gets to the top and it will condense and slide back into the flask at the bottom.
- when the liquid has been collected you raise the temperature until the next one reaches the top
What did John Dalton discover about the atom?
In the early 19th century, John Dalton believed that atoms were solid spheres and different spheres made up different elements.
What did JJ Thomson conclude from his experiments?
That atoms were not solid spheres as his work on charge and mass showed that atoms must contain smaller negatively charged particles.
What theory did JJ Thomson come up with?
Plum pudding model
What is the plum pudding model?
A ball of positive charged with negatively charged electrons in it.
What order were electrons, neutrons and protons discovered in?
Electrons, protons then neutrons
What experiment did Rutherford complete?
Alpha particle scattering experiment
What was Rutherford expecting from the experiment?
The positively charged particles to pass straight through the gold foil or even be slightly deflected.
Why did Rutherford think they would pass straight through the gold foil?
The positive charge of each atom was thought to be spread out through the whole of the ‘pudding’ of the atom
What happened in the alpha particle scattering experiment?
Most alpha particles went straight through the sheet, some were deflected more than expected and very few got reflected backwards.
What did Rutherford do with his results?
He came up with the nuclear model of the atom where there is a small positively charged nucleus at he center where most of the mass is concentrated and a ‘cloud’ of electrons around the nucleus.
Who discovered that atoms are mostly empty space?
Rutherford
What did Bohr realise?
That the electron ‘cloud’ around the nucleus of the atom would be attracted to the nucleus which would cause the atom to collapse.
What did Bohr suggest after realising that the electrons would be attracted to the nucleus?
That the electrons orbit the nucleus in shells
What did further experiments of Rutherford suggest?
That the nucleus is divided into smaller particles which have the same charge as a hydrogen nucleus. These particles are protons
Who discovered neutrons?
James Chadwick
What are the electron rules?
- The lowest energy levels are filled first
- 1st shell= 2 all the others= 8
- atoms are happier when they have full outer shells
How were elements arranged in the 1800s?
Arranged by atomic weight
What are the two ways we categories elements?
- their physical chemical properties
- their atomic weight
Why were early periodic tables not complete?
Elements were placed in the wrong groups as they were ordered in just atomic weight and their properties were not taken into account.
How did Mendeleev order the elements?
Mostly in atomic weight but changed a few elements around if the properties meant it should be changed
Why did Mendeleev leave gaps?
To make sure elements with the same properties could be in the same group so he left space for undiscovered atoms.
How are the elements organised now?
In order of increasing atomic number
Why are elements now organised in this way?
It means they are in repeating patterns in properties of the elements
Where are elements with similar properties found?
Columns- groups
Where are metals and non metals found?
Metals on the left and non-metals on the right
What are column in the peroidic table called?
Groups
What are rows in the periodic table called?
Periods
What does the group number show?
How many electrons are in the outer shell
What does a period show?
How many electron shells an atom has
What ions do metals make?
Positive ions
What ions do non metals make?
They don’t usually make positive ions
Why do atoms react?
To form full outer shells
How do atoms gain full outer shells?
Losing, gaining or sharing electrons
What electron shells feel the most attraction?
The ones closest to the nucleus
What are metals properties?
. strong
. malleable
. great conductors of heat and electricity
. high boiling and melting points
What are the properties of non metals?
. dull
. brittle
. aren’t always solids
. lower density
. generally don’t conduct heat or electricity
Where are transitioning metals found?
The centre of the periodic table
What are group 1 elements called?
Alkali metals
What are properties of group 1 elements?
Reactive and soft
Why are group 1 metals so reactive?
They only have 1 electron in their outer shells
What are the trends of the alkali metals?
- Increasing reactivity as you go down the group
- The melting and boiling points get lower
- The relative atomic mass increases
Why does the reactivity increase down group 1?
The electrons get further away from the nucleus so they feel weaker attraction to the nucleus
What compounds do group one metals make?
Ionic
How do group 1 metals react with water?
. react vigorously
. produce hydrogen gas
. form metal hydroxides that dissolve in water to produce alkaline solution
. the amount of energy released increases down the group
How do group 1 metals react with chlorine?
. react vigorously when heated in chlorine gas
. form metal chloride salts
. reactivity increases down the group
How do group 1 metals react with oxygen?
. form a metal oxide
What are group 7 elements called?
Halogens
How do halogens exist?
As molecules- pairs of atoms
How do group 7 elements change down the group?
. become less reactive
. higher melting and boiling points
. higher relative atomic mass
What compounds can halogens form?
Ionic with metals and covalent with other non-metals
When do halogens form simple molecular structures?
When they react with non metals
What ions do non metals form when reacted with a metal?
1- ions
When does a displacement reaction happen with halogens?
When a more reactive halogen and the salt of the less reactive one react
What are group 0 elements called?
Noble gases
What type of gases are noble gases?
colourless gases
Why are group 0 elements not very reactive?
They have full outer shells
How do the boiling points change in group 8?
Increase as you go down the group
Why does the boiling point trend occur in group 0?
The increase in boiling point is because the number of electrons in each atom increases which leads to more intermolecular forces.
