Periodic table - list of elements, elements in same group have similar properties
Element - each made from different type of atom
Atoms - represented by chemical symbols, tiny nucleus surrounded by electrons, elements reacting - atoms join together = compound formed
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C1.1.2 - Atomic Structure
Atom -> nucleus - centre of atom, contains protons (+) and neutrons (0), electrons (-) - move around nucleus, atom has no charge as no of protons = no of electrons and their charges are equal and opposite
Same element = same no of protons - atomic number = no of electrons, arranged according to atomic number in periodic table
Mass number = no of protons + no of neutrons (electrons have such a small mass that they aren't included)
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C1.1.3 - The Arrangement of Electrons In Atoms
Electron = energy level - represented as shells - lowest energy level nearest the necleus
Lowest energy level (first shell) = 2 electrons, every other = 8 electrons
Elctrons occupy lowest possible energy level
Electronic structure - amount of electrons in each shell
Same group = same no of electrons in highest energy level
Group 1 - react quickly with H2O and O2
Group 0 - unreactive noble gases - stable arrangement of electrons
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C1.1.4 - Forming Bonds
Elements combine to form compounds
Metal + non-metal = ions -> lose electrons = positive charge, gain electrons = negative charge, oppositely charged ions attract each other strongly - compound with iconic bonds
Chemical formula of ionic compounds tell us simplest ratio of ions
Non-metal + non-metal = covalent bonding and molecules form
Chemical formula of molecule tells us no of atoms in molecule, covalent bonds shown as lines when drawn
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C1.1.5 - Chemical Equations
Reactions - atoms rearrange themselves to form the products, atoms aren't create or destroyed -> no of atoms before = no of atoms after, mass of products = mass of reactants
We write chemical equations to represent reactions -> word equations = names, symbols = numbers and types of atoms
Symbol equations need to be balanced, so no of each atom is the same on each side
Making equations balance - change large numbers in front of fomulae - NOT small numbers
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