chemistry exam Grade 11

Multiplication and Divison Sig Digs

Fewest in question

Addition or Subtraction sig digs

Fewest decimal places in question

How to find Nuetrons

Atomic mass - Atomic number

Which subatomic particles make up most of an atom?

Protons and Nuetrons

Metals location on periodic table

Left side

Metalloids location on periodic table

Staircase

Non metals location on periodic table

Right side of staircase

What are periods?

Horizontal rows on periodic table, determine number of electron shells in an atom

What are groups?

Vertical columns on periodic table, have same number of valence electrons

Which Group are Alkali Metals? And what are some characteristics

Group 1, very reactive, soft metals, low density, reactivity increases down the group

What group are alkaline earth metals? And what are some characteristics

Group 2, reactive(not as much as alkali), harder and denser then alkali metals, form alkaline compounds

What group are Halogens? What are some characteristics

Group 17, very reactive non-metals, form salts with metals, reactivity decreases down the group

What group is Noble gases? What are some characteristics

Very interactive, colourless odourless gas, don’t usually form ions

What are isotopes?

Atoms of same element with same number of protons but different number of neutrons

What does the top number mean in an isotope?

Mass number

What does the bottom number mean in an isotope?

Atomic number

What is isotopic abundance?

How common each isotope is in nature, all isotopic abundances add up to 100%, is used to calculate an elements average atomic mass

What is atomic radius and what is the trend?

Size of an atom, distance from nucleus to the outer most shell, as you go down a group increases, as you go down a period decreases

What is electronegativity and what is the trend?

Ability to attract electrons toward itself when forming a bond, increases up a group, increases down a period

What is ionization energy and what is the trend?

Energy required to remove one electron from a neutral atom, increases up a group, increases down a period

What is Electron affinity and what is the trend?

Energy change when an atom gains an electron (more negative : electron gain is more favourable), more favourable up a group, more favourable down a period

Size of positive ions

Fewer shells, smaller then original atom

Size of negative ions

Larger then original atom

Formula for EN

EN 1 - EN 2

0.0-0.4 Range for EN

Non polar covalent

0.5-1.7 range for EN

Polar covalent

>1.8 range for EN

Ionic

How to determine if a molecule is polar or non polar off of structure

Only polar if it has polar bonds and an asymmetrical shape so the bond dipoles do not cancel

When do incomplete octets happen

Not 8 valence electrons in structure, or odd number of valence electrons

Which rows cannot be expanded

2nd row and 1st row, max valence is 8

Which rows can be expanded

3rd row and above

Formula for Lone pairs

LP = valence electrons - 8(lone atoms) / 2

Which atom gets final electron if there’s one left?

more electronegative one

How can you tell how many bonds an atom wants to form?

If it is 4 valence electrons or above, it wants to form enough to get to 8, if it is 3 valence electrons or below, it wants to form enough to get rid of valence electrons

London Dispersion Forces

Found in non polar molecules, happens when a momentary shift in electron density within electron cloud, stronger when larger

Dipole-Dipole forces

Found between two polar molecules, when two atoms attract due to being opposite

Hydrogen Bond forces

Interaction between Hydrogen and Nitrogen, Oxygen, Fluorine, the more hydrogen atoms the stronger

Ranking of intermolecular forces strength

1. Hydrogen bonding

2. Dipole-Dipole

3. London Dispersion Forces

Non polar molecules can have only which force?

London Dispersion Forces

How does melting/boiling point relate to intermolecular forces?

The stronger the intermolecular force, the higher the melting/boiling point is

What is an ionic compound?

Metal + non-metal

What is a molecular compound?

Non-metal + Non-metal

What are some properties of ionic compounds?

High BP and MP, hard and brittle, only conduct when molten or aqueous, and often soluble

What are some properties of Molecular compounds?

Low BP and MP, soft, no conductivity, solubility depends on polarity

What structure do ionic compounds have?

3D crystal lattice, no individual molecules, held together by strong electrostatic attractions in all directions

What structure do molecular compounds have?

Individual molecules with covalent bonds inside each molecule, held together by weak intermolecular forces