Chemistry

Question 1

Explain atoms

Answer 1

• All matter is made up of tiny particles called atoms
• Smallest particle still characterizing a chemical element
• Made up of subatomic particles
• 4 atomic theories developed over time

(Billiard Balls → Raisin Bun → Solar System → Energy level)

Question 2

What are subatomic particles?

Answer 2

• Particles that make up the atom (including electrons, neutrons, and protons)

Question 3

Deescribe the components of an atom

Answer 3

[The atom’s nucleus is made up of protons and neutrons, which altogether make up most mass of the atom]

• Protons (p⁺) can NEVER change, otherwise is a different element
• Neutrons (n^o) can change
• Electrons (e^-) organized into energy levels, outside nucleus, can change

Question 4

What is an isotope? How do you write an isotope?

Answer 4

Atoms of the same element with different # of neutrons

Written as Name-Mass #

^{mass #} ELEMENT SYMBOL

^{atomic #}

Question 5

Describe nuclear notation

[How to find # of protons? / What does the atomic mass number represent? / How to find neutrons?]

Answer 5

Atomic Number = # of protons & electrons, states what element

Mass number = # of protons & Netrons

of neutrons = mass # – atomic #

Question 6

What types of elements can be found on the periodic table? Where can they be found, and what properties do they have?

Answer 6

Metals

• Left side of staircase
• Properties; ductile, malleable, conductive

Non-metals

• Right side of staircase
• Properties; dull, non-conductive

Metalloids

• On staircase
• Properties; brittle, some shiny, some conductive, poor conductors

Question 7

What are ions?

Answer 7

Atoms that have gained or lost electrons to become stable & postively or negatively charged

Cations (+):

• Positive ions (loss of electrons)
• Metals
• End is ion

Anions (-):

• Negative ions (gain electrons)
• Non-metals
• End is -ide (ie. Fluoride)

Question 8

What elements are diatomic in their most natural state?

Answer 8

Iodine, bromine, chlorine, fluorine, oxygen, nitrogen, hydrogen, phosphorus (4), sulfur (8)

I₂ Br₂ Cl₂ F₂ O₂ N₂ H₂ P₄ S₈

I bring clay for our new house 4pouring 8sidewalks

Question 9

What does a Bohr’s Energy level diagram include? What are valence electrons?

Answer 9

Includes: atomic symbol, # of protons, # of neutrons, # of electrons, and energy levels

Energy level organization:

1^st energy level: 2 electrons (max)

2^nd energy level: 8 electrons (max)

3^rd energy level: 8 electrons (max)

(*288)

Valence electrons: electrons located on outermost shell

• Group # atom belongs to = # of electrons on outermost shell*
• Period # atom belongs to = # of energy levels*

Question 10

What happens when electrons absorb a specific quantity of energy? What happens when they emitt that same quantity?

Answer 10

Absorb specific quantity of energy: move ↑_^UP to higher energy level

Emitt same quantity: move ← ^_BACK to original energy level

Question 11

What does a lewis dot / electron dot diagram include? Is there a difference between atom diagrams & ion diagrams?

Answer 11

Atom:

Includes: atomic symbol, # of valence electrons

ie:

^_☻

Na

Ion:

Includes: atomic symbol, # of valence electrons, square [] brackets (charge is displayed outside)

ie:

^_☻☻

[ ^_☻☻ Na ^_☻☻] +

^_☻☻

Question 12

Explain the sections of the periodic table

(ie. Which groups are the most reactive?, When you go down a group, it becomes ______?, What properties do these sections have?)

Answer 12

When you go down a group, it becomes more reactive

Alkali metals (group 1) & Halogens (group 17) are the most reactive

Alkali metals (group 1): very soft, malleable, ductile, react easily with other substances

Alkaline Earth Metals (group 2): malleable, ductile, react with oxygen to form oxides

Transition metals (group 3-12)

Halogens (group 17): react with metallic elements, forms salts

Noble gases / Inert gases (group 18), unlikely to take part in chemical reactions

Question 13

What is the octet rule? Any exceptions?

Answer 13

Octet rule: have 8 electrons on outer shell to become stable by gaining, losing, or sharing electrons.

[EXCEPTION: Hydrogen, Lithium, Beryllium only need 2 electrons (Helium is the closest noble gas)]

Question 14

Describe ionic compounds (properties, naming, formation, electrons, etc.)

Answer 14

• Metal (+) and Non-metal (–)
• Metal named first, non-metal second, 2^nd element is -ide
• Attracted by opposite charges (positive and negative)
• Transfer valence electrons
• Crystal Lattice is produced as solid; crystal shapes with flat sides as regular repeating pattern of ions
• High melting points - lot of energy required to break strong bonds
• Non-conductive when solid (non electrolyte) unable to seperate into + & - charges,
• If melted/dissolved in solution becomes conductive (electrolyte) can seperate into opposite charges

Question 15

Describe covalent (molecular) compounds (properties, naming, formation, electrons, etc.)

Answer 15

• Non-metal & non-metal
• Element named first goes first, 2^nd element ending is -ide
• Uses prefixes (mono, di, tri, penta, etc.), never use mono for 1^st element
• Share valence electrons
• Low melting points - attractive forces between molecules are weak, easy to overcome
• Non-electrolytes - never conduct electricity, do not seperate into positive and negative ions as solid or dissolved.
• Intramolecular bond (within molecules)

Question 16

Desrcibe the different types of ionic compounds.

Answer 16

Binary ionic: just 2 elements

Multivalent ionic: metal elements that have more than 1 possible charge, when writing the name of the formula use roman numerals (stock system) to indicate charge (I,II,III,IV,V, etc.)

Polyatomic: more than 2 elements, ending does not change, listed as second unless NH₄

Question 17

What happens to the metal and the non-metal when the compound is formed?

Answer 17

Metals:

Tend to lose valence electrons, become positive

Non-metals:

Tend to gain valence electrons, become negative

Question 18

List the properties of acids and bases

Answer 18

Acids:

• Taste sour
• Corrode metals
• Turn litmus red
• pH lower than 7
• contain H⁺ _(aq) (hydrogen) ions

Bases:

• Taste bitter
• Feel slippery (“soapy”)
• Turn litmus blue
• pH higher than 7
• contain OH^- _(aq) (hydroxide) ions

Question 19

The more ions in an acid the more ____ it is

Answer 19

The more ions in an acid the more acidic it is

[More ions create a stronger acid]

Question 20

What does Arrhenius’ theory of acids and bases state?

Answer 20

• Only behave as acids/bases when dissolved in water (otherwise just regular compounds)
• Must always be written with (aq)
• Both conduct electricity (electrolytes), (solutions must contain freely moving positive and negative ions)

Question 21

How would you write the chemical formula for water? Is it ionic or covalent? (Include IUPAC name)

Answer 21

Water is covalent

IUPAC name:

dihydrogen monoxide

Chemical formula

H₂O

Question 22

List the (seven) properties of water

Answer 22

Intermolecular bonds: hydrogen bond between water are the strongest overall type of intermolecular bond (forces of attraction between molecutes

High BP & MP: lots of energy is required to increase temperature and break bonds

Surface tension: sticks strongly together (forms droplets)

Ice floats in water: less dense, forms large open pattern of polar molecules when frozen

Concave meniscus: sticks to itself + other surfaces because of large forces of attraction between molecules (like the sides of the container)

Capilliary action: draws water up

Polarity: bent, electrons pulled more strongly to O (slight -), less with H (slight +)

Question 23

What is a physical change? What illustrates that it has occured?

Answer 23

Change to a substance where the chemical composition stays the same

• Shape change
• Phase change: moving from solid liquid, or gas
• Size change: increasing/decreasing

Question 24

What is a chemical reaction? What evidence supports that it has occured?

Answer 24

When one or more substances change to form new substances

Evidence of a chem. reaction:

• Energy change: can be observed as teperature change, light emission, sound emission, electricity.
• Odour change: in some chem. reactions, the odour of the products differs from the odour of the reactants. (ie. odour of food after cooking)
• Colour change: in some chem. reactions, the colour of the product(s) differ from the colour of the reactants (ie. substances in bleach react with coloured compounds to form colourless compounds)
• Formation of a gas: gases are formed in solute chemical reactions (When the reaction takes place in a solution, you can observe the gas being formed as tiny bubbles)
• Formation of a solid (precipitate) in solution: in some chem. reactions, a substance is formed that is insoluble & comes out of solution as solid (ie. soap scum)

Question 25

All chemical reactions involve…

Answer 25

a change in energy

Question 26

Explain exothermic and endothermic reactions

Answer 26

Exothermic:

• Release energy (“Hot”),
• More energy is released when new bonds are formed
• In a chemical equation, energy is a product

[ie: burning gasoline]

Endothermic:

• Absorb energy (“Cold”)
• More energy is required ot break bonds
• In a chem. equation, energy is a reactant

[ie: baking]

Question 27

What does the law of conservation of energy state? What does the law of conservation of mass state, and how does this apply to chemical equations?

Answer 27

Law of conservation of energy:

“Energy can be converted from 1 form to another but the total enrgy in the universe remains constant”

Law of conservation of mass:

“Matter cannot be created or destroyed”

Therefore,

during a chemical reaction the total mass of the reactants is always equal to the total mass of the products.

[reactant’s mass = product’s mass]

Question 28

What is Avogardo’s number?

Answer 28

6.02 x 10²³ (6.02214199 x 10²³), how many carbon atoms there are in 1 mol of carbon

Question 29

What is a mole?

Answer 29

One mole is the amount of particles in an element.

Mass of a mole can change, the # of particles does not.

Question 30

What is molar mass?

Answer 30

Mass of 1 mol of any pure substance, expressed in g/mol, found on the periodic table

Question 31

How do you calculate moles?

Answer 31

n = m ÷ M

n is equal to the number of moles

m is equal to mass (measured in g)

M is equal to molar mass (measured in g/mol)

Question 32

List the types of chemical reactions

Answer 32

Formation (composition): 2+ reactants combine to form a new product [x + y → xy]

Decomposition (opposite of formation): 1 compound breaks down into 2 (or more) simpler compounds or its elements [xy → x + y]

Single replacement: 1 element takes the place of another element in a compound

Double replacement: cations (metals) of 2 different compounds exchange places, forming 2 new compounds [wx + yz → wz + yx]

Neutralization: technically double replacement but more specific [acid + base → salt (ionic) + water]

Hydrocarbon combustion: hydrocarbons only contain hydrogen (H) and carbon (C) [hydrocarbon + O₂ → CO₂ + H₂O]

Question 33

Highlight the differences between a closed system and an open system

Answer 33

Closed system: no exchange of matter between the system & surroundings (ie. tightly capped test tube)

Open system: exchange of substances between system & surroundings (ie. open test tube with solution)

Question 34

What is matter?

Answer 34

Anything with mass & volume that takes up space (solid, liquid, gas)

Question 35

What is a mixture & what different types are there?

Answer 35

Mixture: matter that can be seperated by physical means

Heterogeneous mixture: different components are visible, composition is variable [different] (ie. chilli)

Homogeneous mixture (solution): different components not visible, constant composition [same] (ie. coffee)

Question 36

What is a pure substance and what different types are there?

Answer 36

Pure substance: matter that has a definite composition

Compound: 2 (or more) elements chemically combined together, can be seperated into simpler substances

Element: cannot be further chemically broken down, on the periodic table

Question 37

Explain flammable, corrosive, toxic, and reactive/explosive warnings

Answer 37

• Flammable:* readily ignite (burn in air) in a variety of temperature ranges (usually liquids)
• Corrosive*: substances/vapours that can deteriorate the surface of another material
• Toxic:* even in small quantities may poison, cause injury, or death when swallowed, absorbed through skin, or inhaled.
• Reactive/Explosive:* can react with air, water, or another substance to produce toxic vapours or explode

Question 38

How can hazardous materials enter the body?

Answer 38

Inhalation, through skin, injesting it

Question 39

What does WHMIS, MSDS, and HHPS stand for? What are the WHMIS hazardous classes?

Answer 39

Workplace Hazardous Materials Information System

Hazardous classes: a, b, c, d1, d2, d3, e, f

Material Safety Data Sheets

Hazardous Household Products Symbols