Atomic Structure and the Periodic Table Flashcards
Facts about the nucleus:
In the middle of an atom.
Contains protons and neutrons.
Positive charge because of the protons.
Almost whole mass of atom is found in the nucleus.
Facts about electrons:
Move around the nucleus in electron shells.
Negatively charged.
Have virtually no mass.
What charge are atoms and why?
Neutral, they have the same number of protons as electrons.
What does the atomic number tell you?
How many protons there are.
What does the mass number tell you?
How many protons and neutrons there are.
How do you get the number of neutrons?
Subtract the atomic number from the mass number.
What is an element?
A substance made up of atoms that all have the same number of protons in their nucleus. e/g Nitrogen will have a different number of protons in its nucleus compared to Oxygen.
How many different types of elements are there?
100
What is an isotope?
A different form of the same element, which have the same number of protons but a different number of neutrons.
What is the relative atomic mass?
the average mass of an element, taking into account the different masses and amounts of all the isotopes that make up that element.
What is a compound?
When two or more elements are combined together and are held by chemical bonds.
How are two elements bonded together?
Usually involves atoms giving away, taking or sharing electrons. The nucleus of an atom is never affected.
What is an ion?
- Ions are positively or negatively charged particles formed when atoms loose or gain electrons.
- They have the same stable electronic structures as noble gasses.
- The metal atoms lose electrons to form positive ions and the non-metal atoms gain electrons to form negative ions.
- The opposite charges are attracted to each other.
What is covalent bonding?
- A compound formed from non-metals consists of molecules.
- Each atom shares an electron with another atom.
e/g Hydrogen Chloride
What is a mixture?
When two or more elements or compounds are mixed together.
How can a mixture be separated?
- Filtration
- Crystallisation
- Simple Distillation
- Fractional Distillation
- Chromatography
Are the chemical properties of a substance affected by it being part of a mixture?
No
How do you do Paper Chromatography?
- Draw a line near the bottom of the sheet of filter paper in pencil.
- Add a spot of ink to the line and placed the sheet in a beaker of solvent, e.g water.
- Make sure the ink isn’t touching the solvent.
- Place a lid on top of the container to stop the solvent evaporating.
- The solvent seeps up the paper, carrying the ink with it.
- Each different dye in the ink will move up the paper at a different rate so the dyes will separate out. Each day I will form a spot in a different place.
- The end result is a pattern of spots called a chromatogram.
How does Filtration work?
Filtration can be used if your product is an insoluble solid that needs to be separated from a mixture. It is done by using filter paper over a beaker to separate the solid from the liquid.
How does evaporation work?
- Pour the solution into an evaporating dish.
- Slowly heat the solution. The solvent will evaporate and the solution will get more concentrated. Crystals will start to form.
- Keep hearing the evaporating dish until all you have left if crystals.
How does crystallisation work?
- Pour the solution into an evaporating dish and heat it. Some of the solvent will evaporate and the solution will be more concentrated.
- When you see crystals start to form, remove from heat and leave to cool.
- The salt should start to form crystals as it becomes insoluble.
- Filter the crystals out of the solution and leave them in warmth to dry.
How does simple Distillation work?
- Used for separating out a liquid from a solution.
- The solution is heated. The part of the solution that has the lowest boiling point evaporated first.
- The vapour is then cooled, condensed (in a condenser) and is collected (in a beaker).
- The rest of the solution is left behind in the flask.
- The problem with this is that you can only use it to separate things with different boiling points, otherwise they will mix again.
How does fractional distillation work?
- Put your mixture in a flask and put a fractionating column on top. Heat it up.
- They will evaporate at different temperatures due to their various boiling points.
- The liquid with the lowest boiling point evaporates first, it will rise up the fractioning column filled with glass rods to the top.
- Liquids with higher boiling points may start to evaporate, however the column is cooler at the top so they will only get part way up before condensing and going back down the flask.
- The liquid will go from the top of the fractionating column to the condenser where is it condensed and then the different fractions are collected.
Brief timeline of the atom:
John Dalton J J Thompson Rutherford Bohr Chadwick
