C4
- Created by: superlouasaur
- Created on: 22-04-15 18:40
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- C4
- Atoms
- Atoms make up everything
- Nucleus made up of protons and neutrons- positive charge
- Electrons move around the nucleus
- Protons are heavy and positively charged
- Neutrons are heavy and neutral
- Electrons are tiny and negatively charged
- Number of protons= number of electrons
- Neutral atoms have no charge overall
- Each element has a different number of protons
- Chemical equations
- Atoms aren't lost or made in chemical reactions
- Still have the same atoms just rearranged
- There must be the same number of atoms on both sides
- Method: just balance one type of atom at a time
- Line spectrums
- Some elements emit distinctive colors when heated
- Each element gives a characteristic line spectrum
- When electrons become excited release energy as light
- Different elements emit different wavelengths of light, due to different electron arrangements
- Line spectrums have identified new elements
- History of the periodic table
- Dobereiner tried to organize elements into triads
- The middle element had a relative atomic mass that was the average of the other two
- Newland's law of Octaves
- They didn't have similar products
- He mixed up metals and non-metals
- He didn't leave any gaps
- Every 8th element had similar properties
- Mendeleev left gaps and predicted new elements
- With 50 known elements
- Similar properties in vertical groups
- Left gaps for new elements
- Dobereiner tried to organize elements into triads
- Modern periodic table
- Elements laid out in order of increasing proton number
- There are repeating patterns in properties
- Non metals on the right
- Similar properties are in collumns
- Vertical collumns are called groups
- Electron shells
- Electrons always occupy shells (sometimes called energy levels)
- Lowest energy levels are always filled first
- Atoms like having fill outer shells, not full makes them want to react
- 1st shell only holds 2, the rest hold 8
- Ionic bonding
- Ions are made when atoms gain or lose electrons
- A shell with one electron wants to get rid of it
- All group 1 elements have one electron in outer shell- when lostthey become positive
- transferring electrons forms ionic bond
- oppositely charged ions are strongly attracted to each other
- Regular lattice , can conduct if molten or dissolved in water
- Ions and formulas
- The charges in an ionic compound add up to zero
- If ions have different size charges, you need to put in some numbers to balance things up
- If you know the formula of a salt and the charge on one of the ions, you can work out the charge on the other Ion
- Group 1- Alkali metals
- Lithium, sodium and potassium
- All have one outer shell electron
- Become more reactive as you go down because the outer electron is easier lost- further from nucleus
- Have higher density lower down because atoms have more mass
- Reaction with cold water produces hydrogen gas
- Reaction with chlorine produce salts
- Group 7 halogens
- Chlorine, bromine and iodine
- 7 outer electrons
- Diatomic molecules- pairs of atoms
- become less reactive as you move down
- Outer electrons are further from the nucleus and so additional electrons are attracted less strongly
- Non metals with coloured vapours
- React with alkali metals to make salts
- React with iron to make coloured solids ( iron halides)
- Displacementreactions mean the less reactive elements in a compound are pused out by more reactive ones
- Atoms
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