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Section 1- Principles of Chemistry (part 2)
- Electron Shells
- Nucleus
- 1st Shell= 2 electrons
- 2nd Shell= 8 electrons
- 3rd Shell= 8 electrons
- 3rd Shell= 8 electrons
- 2nd Shell= 8 electrons
- 1st Shell= 2 electrons
- Atoms= happy when they're outer shell is full
- Therefore they react with other atoms to complete their shells
- Therefore they react with other atoms to complete their shells
- Electronic configuration= 2,8,8 ect..
- Nucleus
- Ionic Bonding+ Ionic Compounds
- ALL ATOMS WANT THEIR LAST
SHELL TO BE FULL
- If the atom only has 1 electron in its
outer shell then it wants to get rid of it.
- This atom would love to react with one with 7 in its outer
shell because this one wants one more, there's too many to
give away!
- This atom would love to react with one with 7 in its outer
shell because this one wants one more, there's too many to
give away!
- ion: "an atom or molecule
with a net electric charge due to the loss or
gain of one or more electrons"
- Group 1 and 2 elements are metals and lose
electrons to form +ve ions (cations)
- Group 6 and 7 elements are non-metals and
gain electrons to form -vs ions (anions)
- ALL ATOMS WANT THEIR LAST
SHELL TO BE FULL
- Covalent Bonding+ Covalent substances
- A covalent bond is a shared pair of electrons
- Both atoms have a full outer shell and they are happy
- Strong attraction between the shared
electron pair and the nuclei of the atoms
involved
- Diamond+Graphite
- Diamond=hardest substance in
world! +makes 4 bonds per
carbon atom
- Graphite= Conducts electricity+makes 3
bonds per carbon atom
- Diamond=hardest substance in
world! +makes 4 bonds per
carbon atom
- A covalent bond is a shared pair of electrons
- Balencing Equations
- Word Equation= copper + oxygen = copper oxide
- Symbol Equation= 2Cu + O2 = 2CuO
- Symbol Equation= 2Cu + O2 = 2CuO
- State symbols= Solid (s) Liquid
(l) Gas (g) Aqueous (dissolved
in water (a))
- Practise Questions
- You have to have the same amount of
everything on either side of an
equation or it will be sad
- Word Equation= copper + oxygen = copper oxide
- Isotopes and Relative Atomic Mass
- An isotope is a different version of an atom
- Carbon isotopes:
- They have the same number of protons but
a different number on neutrons
- How to calculate relative atomic mass:
- (mass of isotope x % abundance) + (mass of isotope x % abundance)
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100
- E.g. Boron=
(11x80) + (20x10)
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100
- = 10.8
- = 10.8
- E.g. Boron=
(11x80) + (20x10)
------------------
100
- (mass of isotope x % abundance) + (mass of isotope x % abundance)
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100
- An isotope is a different version of an atom
- Relative Formula Mass
- Look at elements atomic mass on periodic table
- Use the numbers to add up masses of formulas
- Use the numbers to add up masses of formulas
- E.g. MgCl2
- Mg= 24
- Cl= 35.5
- 24+35.5+35.5= 95
- Mg= 24
- Look at elements atomic mass on periodic table
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