20F Chemistry Review Part 1 This should be review of stuff learned last year-ish…if you don’t remember it, then you have more work to do to get caught up

Electron (e-) Proton (p+) nucleus Neutron (n0) nucleus orbit/energylevel Proton (p+) nucleus Neutron (n0) nucleus

Number of protons and neutrons (p+ + no) We will not be building Bohr diagrams this course, but you should remember how do use these numbers Number of protons (p+) [OR electrons (e-) since atoms are neutral] Remember electrons are so small as to be essentially “massless” – the whole mass of the atom is really just the number of p+ and no in the nucleus Number of protons and neutrons (p+ + no)

Atoms that have the same number of protons but a different number of neutrons are called Isotopes. At Mass = 1 At Number = 1 At Mass = 2 At Number = 1 At Mass = 3 At Number = 1 These are ALL considered Hydrogen – based on the proton number

An atom that has lost or gained an electron is called an ion Atoms can either gain or lose electrons Gain - negatively charged ion Lose - positively charged ion H neutral atom H+ positive ion (cation) H- negative ion (anion) An atom that has lost or gained an electron is called an ion

Octet rule: atoms react to acquire a full outer shell: Called valence shell Gain an e- from another atom Lose an e- to another atom Share an e- with another atom Ionic bond Covalent bond Note Metals typically lose e- Non-metals typically gain e-

NOTE These numbers might be called “combining capacity” “valences” or “charges” +1 +3 -3 -2 -1 +2 +4/-4 Non-metals gain e- Metals lose e- Remember: The number of the column is equal to the valence electron number. Know that and you figure out the number of electrons lost or gained – the ionic charge

Mg Cl Cl S Cl Cl MgCl 2 SCl 2 ionic compound covalent compound - +2 - metal non-metal non-metal non-metal MgCl 2 SCl 2 ionic compound covalent compound - +2 Mg Cl Cl S - Cl Cl Gain / lose – called a “formula unit” Sharing – called a “molecule” A compound has different characteristic properties than the atoms which form it.

I Have No Bright Or Clever Friends Diatomic Elements: Elements that are most commonly found in a covalent bond with itself (not as single atoms) I Have No Bright Or Clever Friends I2 H2 N2 Br2 O2 Cl2 F2 NOTE “Greediest” elements that must have a full octet, so they covalently bond with themselves when alone – BUT when bonded to another element there is no longer a reason to be diatomic

Notice: oxygen is not diatomic in a bond… Chemical formula gives the following information: The different elements in the compound The number of atoms in the compound Notice: oxygen is not diatomic in a bond…

Remember the subscript applies to what is directly in front of it Brackets: subscripts outside a bracket multiply by everything inside the bracket. 3 Mg(NO3)2 1 1 Coefficient: total # of molecules present O N Mg O N Remember the subscript applies to what is directly in front of it Mg: 1 · 3 = 3 N: 1 · 2 · 3 = 6 O: 3 · 2 · 3 = 18

Subscripts · Coefficients (type) Compound Coefficient Total of each element Subscripts · Coefficients (type) 2 NaNO3 2 Na: 1 · 2 = 2 (I) formula unit N: 1 · 2 = 2 O: 3 · 2 = 6 2 Al(NO3)3 Al: 1 · 2 = 2 (I) formula unit N: 1 · 3 · 2 = 6 O: 3 · 3 · 2 = 18 3 Ca(OH)2 3 Ca: 1 · 3 = 3 (I) formula unit O: 1 · 2 · 3 = 6 H: 1 · 2 · 3 = 6 4 H2(SO4) 4 H: 2 · 4 = 8 (C)molecule S: 1 · 1 · 4 = 5 O: 4 · 1 · 4 = 16

Writing Ionic Compound Formula 1. Write the symbol of the metallic element first. 2. Place the combining capacity (charge) of one element as a subscript of the other element. 3. Leave subscripts with a value of 1 out. 4. Reduce the subscripts if possible. beryllium combines with chlorine + 2 - 1 Be Cl Be Cl2 1

Naming Ionic Compounds 1. Write the full name of the metal ion first. 2. Name the non-metal ion dropping the ending and adding the suffix “ide.” beryllium combines with chlorine BeCl2 beryllium chlor ide

Here is an example of “reducing” the subscripts Magnesium combines with Sulfur + 2 - 2 Mg S Mg S magnesium sulph ide Here is an example of “reducing” the subscripts

Transition metals

Transition metals can give away different numbers of electrons. To avoid confusion: Brackets are used to show the number of electrons the Transition metal is giving away.

Fe Cl Fe Cl FeCl2 FeCl3 Iron (III) chloride Iron (II) chloride + 2 - 1 1. Write the symbol of the metallic element first. 2. Place the combining capacity (charge) of one element as a subscript of the other element. 3. Leave subscripts with a value of 1 out. 4. Reduce the subscripts if possible.

Pb O PbO lead oxide (IV) +4 -2 Write the name of the ionic compound: + 1 Pb O PbO 1 2 2 lead oxide (IV) Remember: Always look at the anion to see if it has been reduced. If it has, so has the metal.

Prefix Number of Atoms mono 1 di 2 tri 3 tetra 4 penta 5 hexa 6 hepta 7 octa 8 nona 9 deca 10 Memorize this…

Writing Covalent Compound Formula 1. Write the symbol of each element. 2. Use a subscript to show the number of atoms as indicated by the prefix. *Do NOT reduce covalent bonds Prefix Number of Atoms mono 1 di 2 tri 3 tetra 4 penta 5 hexa 6 di phosphorus oxide penta P O 2 5

Naming Covalent Compounds 1. Write the first non-metal with the appropriate prefix. *We don’t use “mono” for the first non-metal 2. Write the second non-metal with the appropriate prefix and add the suffix “ide.” N O 2 4 Prefix Number of Atoms mono 1 di 2 tri 3 tetra 4 penta 5 hexa 6 di nitrogen tetra oxide dinitrogen tetroxide

OCl2 oxygen dichloride MgCl2 magnesium chloride CuCl2 Does it have a metal? YES (ionic) Is it a transition? NO (covalent) NO charges NO criss-cross Use prefixs Ends in “ide” NO YES Find charges Criss-cross Ends in “ide” Find charges Reverse Criss-cross Use Brackets Ends in “ide” OCl2 oxygen dichloride MgCl2 magnesium chloride CuCl2 copper (II) chloride