C1 - Atomic Structure 2 Flashcards
How are compounds formed?
Atoms join together when elements react.
What are compounds?
Substances formed from 2+ elements, atoms are in fixed proportions throughout the compound and they’re held together by chemical bonds.
Making bonds
Involves giving atoms away, taking or sharing electrons.
Only electrons are involved.
Ionic compounds
Formed from a metal and non-metal consists of ions.
Metal atoms lose electrons to form positive ions.
Non metal atoms gain electrons to form negative ions.
Ionic Bonding
Positive attracts Negative
Negative attracts Positive
Compounds which are bonded ionically are sodium chloride and magnesium oxide.
Covalent Bonding
Compound formed from non metals consists of molecules.
Atoms shares an electron with another atom.
Properties of a compound
Totally different from original elements.
A magnetic metal + sulfur (iron sulphide) = dull grey lump.
Formula = Atoms in a compound
CO2 = 1 Carbon Atom + 2 Oxygen Atoms.
C + O O = CO2
Sulphuric Acid (H2SO4)
2 Hydrogen Atoms + 1 Sulphur Atom + 4 Oxygen Atoms
What if there’s brackets in the formulae?
Calcium Hydroxide = CA(OH)2 = 1 Calcium Atom + 2 Oxygen Atoms + 2 Hydrogen Atoms
If there’s brackets, it means the elements in that bracket will equal how many atoms there are on the outside.
How are chemical equations written?
Molecules on the left hand side are reactants.
Molecules on the right hand side are products (produced from the reactants)
Reactants –> Products of reactants
Symbol Equations
2Mg + O2 —> 2MgO
Magnesium + Oxygen —> Magnesium Oxide
Balance of Symbol Equations
- Must always be the same number of atoms on both sides.
- You balance the equation by putting numbers in front of formulas.
Example of symbol equation
H2 S1 O4 + Na1 O1 H1 —> Na2 S1 O4 + 2H2 O
H2 S1 O4 + Na1 O1 H1 —> Na2 S1 O4 + H2
H2 S1 O4 + 2Na1 O1 H1 —> Na2 S1 O4 + 2H2 O
