Science Unit B 3-4

Question 1

Models of compounds

Answer 1

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Question 2

Ionic compounds

Answer 2

pure substances formed as a result of the attraction between particles of opposite charges, called ions.
Properties:

1) High melting point
2) Good electrical conductivity
3) Distinct crystal shape
4) All ionic compounds are solids at room temperature

When the ionic compound is dissolved in water, the metal and non-metal form an aqueous solution of ions.
An ionic compound is formed from a metal and nonmetal.

Question 3

Polyatomic ions

Answer 3

Some ions can also form when certain atoms of elements combine. These ions are called polyatomic ions.
Polyatomic ions are a group of atoms acting as 1.
For example, one atom of carbon and three atoms of oxygen form the polyatomic ion called carbonate or CO32–. consists of more than one atom.

Question 4

How an ion becomes charged

Answer 4

an ion is an electrically charged particle produced by either removing electrons from a neutral atom to give a positive ion or adding electrons to a neutral atom to give a negative ion. When an ion is formed, the number of protons does not change.
(An ion is formed by adding or eliminating electrons)

Question 5

aqueous solutions

Answer 5

For aqueous solutions (substances dissolved in water),

a subscript in parentheses is added to the formula (aq).

Question 6

Molecular compounds

Answer 6

When non-metals combine, a pure substance called a
molecule or a molecular compound is formed.
Molecular Compounds at room temperature can be :

1) They can be solids, liquids, or gases at room temperature.
2) They tend to be insulators, or poor conductors of electricity.
3) They also have relatively low melting and boiling points because the forces between the molecules are weak

Molecular compound forms when two non-metals combine.

Question 7

Naming ionic and molecular compounds

Answer 7

Ionic
The chemical name of the metal or positive ion goes first, followed by the name of the non-metal or negative ion.
The name of the non-metal negative ion changes its ending to ide.
one exception – Where negative ions are polyatomic ions, the name remains unchanged.

Molecular
The first element in the compound uses the element name—just like ionic compounds.

2. The second element in the compound has the suffix ‘ide’—just like ionic compounds.
3. When there is more than one atom in the formula, a prefix is used which specifies the number of atoms.

An exception to rule 3 is when the first element has only one atom, the prefix mono is not used.

Question 8

Subscripts vs superscripts; states

Answer 8

A superscript ( + ) or a ( – ) are used to indicate the charge. Subscripts tell you the number of atoms of that element.

Question 9

Writing chemical formulas for ionic and molecular compounds

Answer 9

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Question 10

what is a chemical reaction

Answer 10

where 2 or more substances combine to form a new substance. (change not reversible)

Question 11

Reaction types

Answer 11

Simple composition –> O+H²O -> H²O²
Decomposition –> 2H²O -> 2H² + O²
Single replacement–> 2 Na + 2 HCl -> 2 NaCl + H²
Double replacement–> HCl +NaOH -> H²O +NaCl

Question 12

Reactions involving oxygen: combustion, corrosion, cellular respiration (REVIEW MORE EXAMPLES) (Study)

Answer 12

Among the most common types of chemical reaction are those involving oxygen
Combustion - a chem reaction that occurs when oxygen reacts with a substance to form a new substance and give off energy. EX: wood lighting wood on a fire. (Combustion is a fast reaction and gives off energy) (remember the triangle of the 3 components - fuel, heat, air.)
Corrosion - the slow chemical change that occurs when oxygen in the air reacts with a metal (rust) (Is a slow change)
Cellular respiration - food reacts with oxygen to produce energy, water and carbon. (takes place in the cells in your body) (In living things)

Question 13

Endothermic vs exothermic reactions

What will happen in a exothermic reaction?

Answer 13

Exothermic - chem reaction that releases heat energy
Endothermic - chem reaction that absorbs heat energy

Because exothermic involves heat, the temp will increase as the reaction proceeds.

Question 14

Law of conservation of mass (re study)

Answer 14

The total mass of the products is always the same as the total mass of the reactants. It states that matter is not created or destroyed in a chemical.

Question 15

Applications of the law of conservation of mass

Answer 15

For example, when wood burns, the mass of the soot, ashes, and gases equals the original mass of the charcoal and the oxygen when it first reacted.

Question 16

Closed system vs Opened system

give example

Answer 16

Open- allows materials or energy to enter + leave

Closed- does not allow material or energy to leave or enter

Question 17

4 factors that affect reaction rate (study)

Answer 17

Catalysts - substances that help a reaction proceed faster (exists in enzymes)
The concentration of reactants- the greater the concentration, the faster the reaction
The temperature of the reactants - the more heat added, the faster the reaction (the particles are moving faster because of more energy added from heat)
The surface area of reactants - the greater the surface are, the more area is available for reaction

Question 18

Enzymes

Answer 18

Something that breaks down things/particles and a type of catalyst.

Question 19

roman numerals

Answer 19

Roman numerals are used in naming ionic compounds when the metal cation forms more than one ion.

Question 20

What is a Formula (study)

Answer 20

identifies the elements in the compound and the

amount of each element.

Question 21

Guyton de Morveau

Answer 21

created a naming system, or nomenclature, for compounds