Topic 1 atomic structure

Topic 1 atomic structure

1. Atoms

   • They contains protons, electrons and neutrons they have a radius of about 0.1nm.
   • The nucleus
     • that is where protons and neutrons are located
     • It has a positive charge due to the protons
     • Most the whole mass of the atom is concentrated in the nucleus
   • the electron
     • they move around the nucleus in electron shells
     • it has a negative charge they are tiny and cover a lot of space
     • They have a no mass
     • Volume of the orbits determines the size of the atom

2. Elements

   • is made up of atoms that have the same number of protons in the nucleus. it consists of one type of atom
   • the proton determines the type of atom

3. Isotopes

   • Different form of the same element that has the same number of protons but different number of neutrons

4. Compuonds

   • The elements react and the atoms react with other atoms to form a compound
   • the atoms of each elements are in fixed proportion throughout the compound and are held together by bonds.
   • Inorder to separate the compound you need a chemical reaction.

5. Mixtures

   • There is no chemical bond between a mixture
   • It can be separated using physical methods such as filtration, distillation, fraction distillation, chromatography and crystallisation
   • Air is a mixture of different gases mainly nitrogen, oxygen, carbon dioxide and argon.
   • Crude oil is a mixture of different length hydrocarbon molecules

6. Metals and non metals

   • Metals are elements which can form positive ions when they react
     • metal they are strong, conduct heat and electricity and they have high boiling points they can also have metallic bonding.
   • Non metals don't generally form positive ions when they react.
     • Non metals aren't solid at room temperature,they don't conduct electricity and they have a low density.

7. Transition metals

   • They have properties of a proper metal.
   • They can form more than one ion e.g copper forms Cu+ and Cu2+
   • They are considered good catalysts

8. Group 1 Elements

   • They are known as alkali metals they are soft, low density and lithium, sodium and potassium are less dense than water.
   • They contain only one electron in the outer shell meaning they are reactive
   • Trend
     • AS you go down reactivity increases because the electron attraction with the nucleus is weak.
     • Lower melting and boiling points.
   • they can react with non metals and form ions.

9. Group 7 elements

   • they are called halogens
   • Trends
     • They become less reactive because its harder to gain electrons.
     • They have higher boiling points
   • They can make molecular compounds due to a covalent bond between a non metal.
   • They can form ions and displacement reaction occurs when a more reactive halogen and the salt of a less reactive and it will displace the less reactive.

10. Group 0 elements

    • they are known as noble gas they don't react because of their full outer shell
    • They exist as monatomic masses meaning single atoms that aren't bonded
    • As you go down the boiling and melting points increase