Unit A - Chemistry

Question 1

Define atomic number

Answer 1

Number of protons in an atoms - all atoms of an element have the same amount of protons.

Question 2

Define base

Answer 2

A base is a compound dissolved in water with a pH level higher than 7.

Question 3

Define compound

Answer 3

A compound is something made up of more than one element.

Question 4

Define electron

Answer 4

An electron is a subatomic particle with a negative charge.

Question 5

Define element

Answer 5

An element is a building block that, when combined with other elements, are the building blocks of all of Earth’s materials.

Question 6

Define energy level

Answer 6

An energy level is a region of space near the nucleus that may be empty or may contain electrons.

Question 7

Define endothermic

Answer 7

When a substance has an endothermic reaction it absorbs energy.

Question 8

Define exothermic

Answer 8

When a substance has an exothermic reaction it releases energy, usually in the form of heat, light, or electricity

Question 9

Define acid

Answer 9

An acid is a compound that dissolves in water to form a solution with a pH level lower than 7.

Question 10

Define “group” in the context of a periodic table

Answer 10

A group (or family) of elements is a vertical column in the periodic table, there are 18 groups.

Question 11

Define ion

Answer 11

An ion is an electrically charged atom or group of atoms

Question 12

Define isotope

Answer 12

An isotope is an atom of an element with a different number of neutrons than another atom of the same element

Question 13

What is the law of conservation of mass?

Answer 13

The law of conservation of mass states that when a reaction occurs, the total mass of products will be equal to the total mass of reactants.

Question 14

What is a molecule?

Answer 14

A molecule forms when two or more non-metallic atoms bond together.

Question 15

Define neutron

Answer 15

Subatomic particle with no electrical charge.

Question 16

Define nucleus

Answer 16

Dense core of positively charged subatomic particles.

Question 17

Define period

Answer 17

A period is a horizontal row. There are seven rows.

Question 18

What is the pH scale?

Answer 18

The pH scale is a measure of acidity.

Question 19

Define proton

Answer 19

A proton is a positive sub atomic particle located in the nucleus of an atom

Question 20

Define valence electron

Answer 20

A valence electron is any electron on the outer energy level of an atom.

Question 21

How does heating food help preserve it?

Answer 21

Heating food temporarily sterilizes it.

Question 22

How does freezing food help preserve it?

Answer 22

Freezing food preserves it almost indefinitely. The very low temperature prevents the growth of micro organisms that cause decay

Question 23

Describe J.J. Thomson’s model of the atom

Answer 23

He suggested that an atom was a sphere of positive charge in which negative particles, known as electrons, were embedded.

Question 24

Describe Rutherford’s atomic model

Answer 24

Rutherford suggested that atoms are mainly empty space through which positive particles could pass as well as a small, positively-charged nucleus. Electrons could only move through the empty space, not through the core.

Question 25

What is the difference between cations and anions?

Answer 25

Cations are positively charged ions, whereas anions are negatively-charged.

Question 26

List three properties unique to acidic solutions

Answer 26

Acids are reactant with metals, turns blue litmus paper red, and acids taste sour.

Question 27

List three properties unique to basic solutions

Answer 27

Basic solutions are non-reactive with metals, are bitter tasting, and turn red litmus paper blue.

Question 28

Name the four chemical families

Answer 28

Alkali metals, alkaline-earth metals, noble gases, and halogens.

Question 29

State the octet rule

Answer 29

The octet rule states that atoms bond in such a way as to have eight electrons in their valence energy level (to be like nearest noble gas).

Question 30

What are some properties of ionic compounds? (4)

Answer 30

High melting point, retention of crystal shape, solubility in water, conductivity in solution.

Question 31

Explain what makes water polar

Answer 31

Water is polar because it has a negative end and a positive end because of its bent shape and unequal sharing of electrons. Oxygen end is negative, hydrogen end is positive.

Question 32

How can you name an acid by its compound formula?

Answer 32

H (the symbol for hydrogen) tends to appear one or more times on the left. COOH may be seen on the right side of the formula.

Question 33

How can you recognize a base from its formula?

Answer 33

There may be the presence of the hydroxide ion (OH-)

Question 34

What is neutralization?

Answer 34

Neutralization is the reaction of acids and bases together, stripping away all acidic/basic qualities.

Question 35

Name two biochemical reactions

Answer 35

Two biochemical reactions are photosynthesis and cellular respiration.

Question 36

Name the characteristics of chemical reactions

Answer 36

All chemical reactions involve the production of new substances, all reactions involve the flow of energy, and a change of state can be observed.

Question 37

How do you balance a formula equation?

Answer 37

To balance a formula equation you must ensure that the amount of atoms on the reactant side of the equation and the product side of the equation are equal.

Question 38

Describe a formation reaction

Answer 38

A formation reaction is when two elements combine to form a compound.

Question 39

Describe a decomposition reaction

Answer 39

A decomposition reaction is the reverse of a formation reaction. The products are broken down to yield to the reactants.

Question 40

Describe a hydrocarbon combustion reaction

Answer 40

A hydrocarbon combustion reaction is the reaction between hydrocarbons and oxygen.

Question 41

Single replacement reaction

Answer 41

A single replacement reaction is when a reactive element reacts with an ionic compound. After the reaction the element ends up in a compound and one of the elements in the reactant compound ends up by itself as an element.

Question 42

Double replacement reaction

Answer 42

Double replacement reactions commonly occur between two ionic compounds. The ions in the first compound join with the ions from the second compound, this type of reaction often results in the formation of a precipitate.

Question 43

What is a mole?

Answer 43

A mole is the quantity that chemists use to measure elements and compounds. Each mole contains the number of particles equal to Avogadro's number.

Question 44

What is Avogadro's number?

Answer 44

6.02x10^23

Question 45

What is the atomic molar mass of an element?

Answer 45

The atomic molar mass of an element is the average mass in grams of one mole of atoms of that element.