Grade 8 Chemistry & Bonding Criterion A Study Guide

What do protons do?

What do protons do?

Determine the charge

What do neutrons do?

Determine the mass

What do Electrons do?

Determine the charge

characteristics of ‘matter

It takes up space and has mass

Atomic number= to what?

number of protons/electrons*

Atomic mass= to what?

total number of protons & neutrons

# of Neutrons = to what?

mass number – atomic number

Periods equal to what

The number of electron occupied shells

Groups = column

number of valence electrons

where to find metals on the periodic table?

on the left side (+transition metals in the center) of the Periodic table

where to find non-metals on the periodic table?

on the right side (+Hydrogens on the left side) of the periodic table

where to find metalloids on the periodic table?

on the staircase-ish section between the metals and nonmetals on the right side

Special group 1

alkaline metals

Special group 2

alkaline earth metals

Special group 16

chalcogens

Special group 17

halogens

Special group 18

Nobel Gas

valence electrons

Electrons are on the outermost shell of an atom

octet rule to the valence shell

1.An atom with 8 valence electrons will be stable

2.An atom with 1 or 7 valence electrons will be most reactive bc it only needs to lose/gain 1 single electron to be stable (to get 8 on the valence shell)

Bohr model

Shows a positively charged nucleus surrounded by electrons in shells based on their energy level.

maximum number of electrons in a non-valence shell

2(n2) where n = period number

predict the number of valence electrons for main-group elements

look at the group number

Apply a method to determine the Bohr structures

1. Find the atomic # atomic #= total # of electrons

2.Find the period #- period #= total # of electron shells, which also can be used to calculate

3. For the main group elements, determine the # of valence electrons using the group rule. To fill other shells starting from the inside shell. For transition metal assume 2 valence electrons, fill the other shell, and then adjust it if necessary

4 Adjust for ions* if necessary

Ion

an atom with a charge

Cation

positively charged ions

Anion

negatively charged ions

Be able to explain that the charge on the atom depends on the number of electrons

Changing the protons would change the element, and since electrons are negatively charged by increasing/decreasing electrons would change the charge of an atom.

Be able to describe what an isotope is, and how isotopes depend on neutrons

variants of an element that has different mass, the mass depends on neutrons that have no charge and are not responsible for changing element types

Be able to explain that an isotope can be stable or unstable.

Since an atoms’ stability depends on the neutrons an Isotope can be both stable and unstable.

Superscript=

Simplified atomic mass

Subscript=

Numbers of atoms of that element

Ph scale

1-6 acidic

8 - 14 is basic

7 is neutral

acidic substance

Acidic substances produce excess hydrogen ions (protons)

Acidic substance example

lemon juice

alkaline substance (a base)

Alkaline substances produce excess hydroxide ions

alkaline substance examples

cleaning detergent

methods of recording ph

Indicator papers: advantages - portable and easy to carry around. Disadvantages - sometimes inaccurate and can have human errors.

pH pen: can be portable but also more accurate than Indicator papers.

pH sensor: very accurate but can only be used inside a lab

Balanced equations

Balanced equations are equations where the elements from the reactants side and product side are equal.

five major types of chemical reaction

Synthesis: two different atoms/molecules combine to form one compound

Decomposition: one compound is broken down to two or more simpler atoms/molecules

Combustion: the products are carbon dioxide (CO2) and water (H2O)

Double replacement: have two compounds that are exchanging metals and non-metals

Single replacement: have two compounds that are exchanging metals/non-metals

signs of a chemical change

Temperature

Burning

Precipitation

Color changes

Odor (smell)

Gas

Forming of bubbles

properties of an ionic compound

High boiling and melting points

properties of a covalent compound

Lower melting and boiling points

Weaker bond than ionic compound

Can be solid liquid or gas at room temperature

Concept of Collision Theory

Collision Theory states that in order for a chemical reaction to occur particles must collide with enough energy (activation energy).

State and use a general formula for the rate of a reaction

(reactants -> products) / time

four factors that influence the rate of reaction

Factor 1: Changing temperature, Factor 2: Changing surface area, Factor 3: Changing the pressure/concentration, Factor 4: Adding a catalyst

Factor 1: Changing temperature.

Increasing the temperature will increase the rate of reaction because more energy is provided for the reaction to take place.

Factor 2: Changing surface area.

Increasing the surface area will increase the rate of reaction because more particles are colliding with each other.

Factor 3: Changing the pressure/concentration..

Increasing the pressure/concentration will increase the rate of reaction because there are higher changes/more particles to collide with.

Factor 4: Adding a catalyst.

Catalysts are substances that increase the rate of a chemical reaction.

The soil sample that would be best for general plant growth is the third sample because it is not as acidic and is neutral.

Synthesis

two different atoms/molecules combine to form one compound

Decomposition

one compound is broken down to two or more simpler atoms/molecules

Combustion

The products are carbon dioxide (CO2) and water (H2O)

Double replacement

have two compounds that are exchanging metals and non-metals

Single replacement

have two compounds that are exchanging metals/non-metals