Chemistry 20 – Review Unit 1Matter Energy and The Periodic Table

What is Chemistry?

Chemistry deals with:

a) what things are made of (matter).

b) properties of matter (characteristics).

c) how matter interacts (chemical reactions).

d) energy changes (energy released or absorbed).

Important Terms in Chemistry:

a) Matter: anything that has mass and takes up space (has volume).

b) Composition: what kinds of particles are in the matter and how many of each.

c) Structure: how the particles are bonded together.

d) Properties: characteristics of matter that are used to identify it.

e) Transformations: changes in matter

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Three types of changes:

i) Phase Change: state of matter (solid, liquid or gas)

Example: H2O(s) H2O(l)

- Solid –

- Liquid –

- Gas –

- Plasma –

definite shape and definite volume

varied shape and definite volume

varied shape and varied volume

gas charged with high energy electricity (Northern Lights – Fluorescent lights)

ii) Chemical Change: atoms within a substance are rearranged to form new substances

Example: 2 H2O(l) 2 H2(g) + O2(g)

iii) Nuclear Change: elements are changed into different elements

Example: nHeHH 10

42

21

31

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Energy: something that gives you the ability to do work

Scientific Methods

Scientists are always making observations.

Observations can be of two types:

Qualitative:

Quantitative:

descriptive statements, using the 5 senses, about what has been observed

For example: colour, texture, descriptive size etc

measured observations, using instrumentsFor example: 5.0 g (mass), 2.75 cm (length), 2.50 L (volume)

Properties of a substance are used to identify a substance. There are 2 types of properties:

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Physical Properties:

 

Chemical Properties:

the characteristics of a substance that do not involve the change in internal composition of a substance

For example: colour, shape, density, melting or boiling point

characteristics of a substance that cause it to change (react) into something totally new

For example: a substance’s ability to react with an acid

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Classification of Matter

Matter

Pure Substances MixturesPhysical Changes

Chemical Changes

Elements Compounds

Metals Nonmetals Metalloids Noble Gases

Ionic Molecular

Homogeneous Heterogeneous

Solution

Acids Bases Salt Solutions

Alloys

SuspensionColloid

Elements: matter that is made up of one kind of atom

Examples:

- metals such as copper (Cu(s)) or mercury (Hg(l)) (monatomic)

- nonmetals such as helium (He(g)),

oxygen (O2(g))(diatomic), ozone (O3(g)) (triatomic),

iodine (I2(s)),

sulfur (S8(s)), phosphorous (P4(s))(polyatomic)

Compounds: substances that are made up of groups of elements chemically bonded and arranged in a specific manner

Pure Substances

Special Compounds:

Minerals:

Oxides:

an element or compound that occurs naturally in the earth

Example: salt (halite)

a compound formed by combining at least one element with oxygen

Example: Fe3O4(s) – rust ( metal + oxygen )

CO2(g) – carbon dioxide ( nonmetal + oxygen )

There are two types of compounds:

Ionic Compounds:

Molecular Compounds:

formed by combining metallic elements with nonmetallic elements

Examples:

- sodium chloride – NaCl(s)

- magnesium hydroxide – Mg(OH)2(s)

- aluminum oxide – Al2O3(s)

formed by combining nonmetallic elements into a unit called a molecule

Examples:

- carbon monoxide – CO(g)

- water – H2O(l)

- ammonia – NH3(g)

- wax – C25H52(s)

Mixtures (Impure Substances)

- contain 2 or more pure substances that are not chemically joined together and mixed in any proportion

- can be physically separated by filtering, boiling or centrifuging

- Example: a container of rocks, sand and water

There are two types of mixtures:

Homogeneous:

- looks completely uniform in composition

- has only one phase

- usually are solutions

Examples:

- sugar dissolved in water (solid in liquid)

- air (gas in gas)

- carbonated water (gas in liquid)

Heterogeneous:

- does not look uniform in composition

- distinctly visible phases

Examples:

- oil and vinegar salad dressing

- chunky peanut butter

Special Mixtures:

Colloid: falls halfway between a homogeneous and heterogeneous mixture as it looks homogeneousbut distinct phases exist upon closer, microscopic observations

Examples:

- milk (liquid in liquid) - gelatin (liquid in solid)

Ore: a rock that has an element that can be obtained for profit

Examples:

- iron ore – Fe2O3(s) - bauxite – Al2O3(s)

Alloy: a mixture of at least two elements, at least one of which is a metal, melted together uniformly

Examples:

- steel – iron and carbon

- stainless steel – iron, carbon, chromium and manganese

Plated Metals:

- a metal object that has been coated with another metal

Examples:

- Nails may be coated with zinc and steel cans are coated with tin to prevent corrosion.

- Some dinner utensils are coated with silver to look more attractive.

Changes in Matter

Physical Changes:

- There are three major types of energy changes:

- phase, chemical and nuclear.

Phase Change:

- There is no change in chemical composition, only the change in phase is noted. As a substance changes from one phase to another, it either absorbs energy (endothermic change) or releases energy (exothermic change).

- Example: H2O(s) H2O(l)

Solid

Liquid

Gas

Plasma

MeltingFusion

Vapourization

Ionization

Su

blimation

De-ionization

Condensation

FreezingSolidification

Dep

osit

ion

Chemical Change:

- The reactant(s) have different chemical composition than the product(s).

- Evidence of a chemical change occurring:

- colour change

- formation of a solid (precipitate) in a solution

- production of a gas (bubbling)

- energy change (heat being lost or absorbed)

Example: 2 H2O(l) O2(g) + 2 H2(g)

Nuclear Change or Transmutation:

- One kind of element is changed to form another kind of element.

Fission: splitting of atoms

Examples:

Alpha Decay 42Ra223

88Th22790

atomic mass

protons

alpha emission

- α: alpha particles or helium nuclei ( ) He42

Beta Decay 01N14

7C146 electron emission

Fusion: atoms coming together

Example: nHeHH 10

42

31

21

Energy and Matter

Kinetic Energy:

- energy of motion

- the mass of an object and how fast it is moving determines the total energy it has

Example: A car travelling at has less energy than when it is

moving at .

hkm10

hkm100

Potential Energy:

- stored energy

- may be due to:

- an object’s vertical position relative to another object

- energy used to push atoms apart

- used to hold subatomic particles together

Examples:

- a ball held 1 m above the ground has more potential energy than being held 0.5 m above the ground

- gasoline has potential energy stored in chemical bonds

- splitting atoms releases stored nuclear energy that holds the subatomic particles together

Law of Conservation of Energy

Energy cannot be created nor destroyed but can only be transformed from one form to another.

Energy

Kinetic Potential

Heat

Mechanical

Sound

Electrical

Light

Chemical Nuclear

Gravitational

The Periodic Table

- Mendeleev created the periodic table to organize elements together based upon similarities of chemical reactions.

- It is made up of 18 vertical columns called groups or families and horizontal rows or series called periods.

1 2 181716151413 3 4 5 6 7 8 9 10 11 12

1A 2A 3A 4A 5A 6A 7A 8A

1

23

4

56

7

Period

Alkali Metals Alkaline Earths

Transition Metals

Nonmetals

HalogensNoble Gases

Lanthanum Series

Actinium Series

Characteristics of Metals

- Shiny or lustrous

- Good conductors of heat and electricity

- Flexible: can be bent or shaped into wire (ductile) or rolled into sheets (malleable)

- All are solids at room temperature (exception: mercury, which is a liquid)

- All have a silver colour, except for gold and copper

Examples: copper (Cu(s)), magnesium (Mg(s))

Characteristics of Nonmetals

- Solids may be dull in appearance or may have a glassy luster

- Poor conductors of heat and electricity

- Varied examples of solids, liquids and gases

- Colours vary

Examples: oxygen (O2(g)), sulfur (S8(s)), bromine (Br2(l))

Characteristics of Metalloids

- Have properties of both metals and nonmetals

- Semiconductors: conduct in some conditions but not others

- All are solids

Examples: carbon (C(s)), boron (B(s)), silicon (Si(s))

Characteristics of Noble Gases

- All are gases

- Least reactive of all elements

- Do not conduct electricity

Examples: helium (He(g)), neon (Ne(g))

- Each element has an abbreviation. Some elements use only one character such as carbon (C) or potassium (P).

- Each element has an abbreviation. Some elements use only one character such as carbon (C) or potassium (K). Others use two characters, the first being capitalized and the second, being lower case, such as calcium (Ca).

- Some symbols are obvious but some have historic origins.

Examples:

Common Name Symbol Latin Name

antimony Sb stibnum

copper Cu cuprum

gold Au aurum

iron Fe ferrum

lead Pb plumbum

mercury Hg hydragyrum

potassium K kalium

silver Ag argentum

sodium Na natrium

tin Sn stannum

The Structure of the Atom

Models of the Atom

Dalton Model – Billiard Ball Model

- Atoms are single, indivisible spheres.

- Molecules are units or groups of atoms arranged in a specific ratio.

Problem: It was found that

a) the atom contained positive and negative parts.

b) the positive part was much heavier than the negative part.

c) the whole atom was electrically neutral

d) opposite charges attract and similar charges repel.

Thomson Model – Raisin Bun Model

- The atom is a large mass of positive charge and has small negative parts embedded in this sphere.

Rutherford Model – Nuclear Model or Empty Space Model

- The atom has a central core that is positively charged.

- Electrons exist in empty space, surrounding this central positive mass, travelling anywhere they want.

3+

Bohr Atom – Orbital Model

- The core of the atom was the nucleus, containing neutral particles called neutrons and positive particles called protons.

- Electrons had different defined amounts of energy, therefore had to exist at specified distances from the nucleus, in orbits.

- This meant that the electron was quantized or had only a certain quantity of energy when found at different energy levels.

3+

Quantum Mechanical Model – Cloud Model

- The electrons move so quickly in their orbital that they create a “cloud-like” behavior.

- Each “cloud” has its own characteristic shape, depending how far away from the nucleus the energy level is found.

Subatomic Particles and The Structure of the Atom

Atom:

- the basic building block of all substances

- contains a central nucleus which houses relatively similarly - sized neutrons (no charge) and protons (positive charge)

- electrons exist in orbitals around the nucleus

Isotopes:

- Atoms that have the same number of protons and electrons (therefore are the same element) but have different numbers of neutrons

- Some elements may have more than two isotopes

Isotopes of Hydrogen

Protium (ordinary hydrogen) H11

1 p+

0 no

1 e –

99.985 %abundance

Deuterium (heavy hydrogen) H21

1 p+

1 no

1 e –

0.015 %abundance

Tritium (radioactive hydrogen) H31

1 p+

2 no

1 e –

negligibleabundance

Particle Symbol ChargeActual Mass

(g)

Mass Relative

to a Proton

Mass Relative

to an Electron

proton p + +1 1.672 x 10 –24 1 1836

neutron n o 0 1.675 x 10 –24 1 (1.002)

1839

electron e – –1 9.11 x 10 –28 0 (0.0005)

1

Atomic Mass

- used to be called atomic weight

- the atomic mass described on a periodic table is the average mass of all known isotopes of that element

- carbon is known to have 6 different isotopes, mass numbers ranging from 10 to 16

- about 98.89 % of all the isotopes have a mass of 12.00000 amu (atomic mass units) and is called carbon – 12

- about 1.11 % of all the isotopes have a mass of 13.00335 amu and is called carbon – 13

- the other four isotopes are very rare and are not found naturally

- if the periodic table gives an atomic mass of carbon as 12.01, that means that the average mass of all carbons is 12.01

- all atomic masses on the periodic table have a unit called grams per mole  (we will discuss the concept “mole” later)

gmol

Electron Energy Level Representations for Atoms

- using the concepts from the Bohr Model of an atom we can give a simplistic sketch of how atoms are put together

Sodium Atom

- since the element sodium has an atomic number 11 on the periodic table, this means that every sodium atom must have 11 protons (11 positive charges)

- since atoms are neutral, there must also be 11 electrons

- the atomic mass is given as 22.99 (round off to 23)

- so, the total mass of a sodium atom is 23, made up of subatomic particles inside the nucleus (11 protons and 12 neutrons – electron mass is too small to count)

The Sodium Atom ( Na )

1st energy level = 1st period

2nd energy level = 2nd period

3rd energy level = 3rd period

2 e –

8 e –

1 e –

11 p+

12 no

The outside energy level contains 1 electron, therefore, tells you that sodium is found in Group IA.

The Fluorine Atom ( F )

1st energy level = 1st period

2nd energy level = 2nd period

2 e –

7 e –

9 p+

10 no

The outside energy level contains 7 electrons, therefore, tells you that fluorine is found in Group VIIA.

Ions

- positive ions are called cations and negative ions are called anions

- ions are atoms that have lost or gained one or more electrons

- the electrons are lost or gained from the last, outside energy level only

- the electrons on the outside energy level are called valence electrons

- if an electron is lost, a negative charge is lost

- losing a negative makes the atom more positive

- if an electron is gained, a negative charge is gained

- gaining a negative makes the atom more negative

The Sodium Ion ( Na+ )

- since the sodium ion is shown as a +1 charge, that means that it has lost an electron from the outside energy level

11 p+

12 no

2 e –

8 e –

1 e –

1st energy level = 1st period

3rd energy level = 3rd period

2nd energy level = 2nd period

- therefore, the sodium ion now looks like this:

11 p+

12 no

2 e –

8 e –

1st energy level = 1st period

2nd energy level = 2nd period

11 p+

12 no

2 e –

8 e –

1 e –

1st energy level = 1st period

3rd energy level = 3rd period

2nd energy level = 2nd period

- the total charge is +1

The Fluoride Ion ( F – )

- note that if you look up the names of the ions formed from nonmetals, their names change to an “ide” ending

- to get an F – ion, you must add one electron to the atom to get a total charge of –1

9 p+

10 no

1st energy level = 1st period

2nd energy level = 2nd period

2 e –

8 e –

Elements, Compounds and Nomenclature

- the term “nomenclature” refers to “naming”

- chemical nomenclature is the organized system chemists use to name substances and write their chemical formulas

- when writing any formula for any substance we first assume that the substance exists on its own, at room temperature

- if special conditions exist, states of matter are adjusted

Naming Pure Elements

Metals

- when naming metals, we simply state the elemental name given on the periodic table

- when writing the formula for any pure metal we simply write the elemental symbol (no subscripts)

- inclusion of states of matter is very important, so we must always indicate a solid state, the exception being mercury, Hg(l)

Nonmetals

- when naming nonmetals, we simply state the elemental name given on the periodic table

- when writing the formula for any pure nonmetal we write the elemental symbol with subscripts for some of the nonmetals, because we must also be aware of how it exists at room temperature

- for most nonmetals, you’ve just got to memorize their formulas and their natural states of matter

- all nobles gases are monatomic: He(g) , Ne(g) , Ar(g) , Kr(g) , Xe(g) , Rn(g)

- diatomic elements include:

- nitrogen – N2(g) - oxygen – O2(g) - all halogens: fluorine – F2(g) chlorine – Cl2(g) bromine – Br2(l)

iodine – I2(s) astatine – At2(s) - polyatomic elements include: phosphorous – P4(s) sulfur – S8(s)

- all other nonmetals are monatomic and solid

Naming Compounds

- a compound is a pure substance made by combining at least two different elements in a specific ratio

Ionic Compounds

- an ionic compound is formed by taking one metallic ion and combining it with one nonmetallic ion or a complex ion

Binary Ionic Compounds

- only one metallic ion and one nonmetallic ion are combined

Process for Creating the Formula:

- find the elements

- list their ions

- place positive ions (cations) first, followed by negative ions (anions)

- criss-cross their charges to create the correct ratio of each element and simplify charges (reduce)

- the state of matter for all ionic compounds is solid

Naming Ionic Compounds

- the first element gets its normal elemental name as found on the periodic table

- the second element’s name has an “ide” ending (regardless of the ratios found in the formula)

Examples:

- sodium and chlorine Na+ and Cl –

join together

Na + Cl –

criss-cross charges

Na –1 Cl +1

simplify subscripts

NaCl (one’s are ignored)

identify state of matterNaCl(s)

name the compound

sodium chloride

- magnesium and iodine

Mg 2+ and I –

Mg 2+ I –

Mg –1 I 2+

MgI2

MgI2(s)

magnesium iodide

- oxygen and aluminum

Al 3+ and O 2–

Al 3+ O 2–

Al –2 O +3

Al2O3

Al2O3(s)

aluminum oxide

- oxygen and calcium Ca 2+ and O 2–

Ca 2+ O 2–

Ca –2 O +2

Ca2O2 *note: subscripts are simplified for ionic compounds

CaOCaO(s) calcium oxide

Creating the Formula and Naming Ionic Compounds Using Complex Ions

- when a simple positive ion is combined with a complex ion the process is as follows:

- list both positive and negative ions - combine both

- use brackets for the complex ion - criss-cross their charges

- simplify subscripts

- when naming the compound, use the normal first name for the metallic ion and copy the given name of the complex ion, which is found in the complex ion table

Example: - calcium and hydroxide Ca 2+ and OH –

Ca 2+ and (OH) –

Ca –1 (OH) 2+

Ca1(OH)2

- since 1’s are not required

Ca(OH)2(s)

- note that if a 1 should appear after the brackets, the brackets are not required

Naming Ionic Compounds Using Multiple Ion Charges

- some metallic ions have more than one charge

- for example, iron has Fe2+ and Fe3+

- in these cases it is necessary to actually state which ion is being used

- Roman numerals are used after each multiple-charged ion

Example iron and oxygen

Fe2+ and O2 –

FeO(s) named iron (II) oxideor

Fe3+ and O2 –

Fe2O3(s) named iron (III) oxide

- some tables may use old, “classical” names that end with “ic” or “ous”

- “ic” ending is for the ion that has the greater charge

Example

Fe3+ is also called ferric

Fe2+ is also called ferrous

FeO(s) is also called

ferrous oxideFe2O3(s) is also called

ferric oxide

Hydrated Compounds

- some compounds have a strange-looking formula which has water added at the end, such as CuSO4 5 H2O(s)

- these are still ionic compounds and exist as solids at room temperature

- the only thing we have to do is to state how many waters are involved

- so, for CuSO4  5 H2O(s) , the first part is named as copper (II) sulfate

and then we add that there are 5 waters

- the Latin prefix for 5 is penta and water is called hydrate

- the name becomes copper (II) sulfate pentahydrate

# Latin Prefix

1

2

3

4

5

6

7

8

9

10

mono

di

tri

tetra

penta

hexa

hepta

octa

nona

deca

Naming Molecular Compounds

- molecular compounds are formed by combining nonmetallic elements

- when these elements are combined they may form more than one compound

- carbon and oxygen may combine to form CO(g) or CO2(g)

- nitrogen and oxygen may combine to form NO(g) or NO2(g) or N2O4(g)

- note that subscripts are not simplified and another naming system is used

Example

- CO2(g) is made from carbon and oxygen

- the first element gets the normal name

- the second element gets and “ide” ending

- now we must state how many of each element is being used by inserting prefixes before each element name

- there is one carbon (monocarbon) and two oxygens (dioxide)

- if the first element is a “mono” the prefix is ignored but is used for the second element

- NO(g) is nitrogen monoxide

- NO2(g) is nitrogen dioxide

- N2O4(g) is dinitrogen tetroxide

- there is no general rule for determining states of matter

- each molecular compound has its own characteristic state of matter at room temperature and these are learned as you go along

- some molecular compounds have classical names that have no logic involved in their naming system

- these we just memorize

Examples H2O(l) is

NH3(g) is

O3(g) is

CH4(g) is

C6H12O6(s) is

C12H22O11(s) is

CH3OH(g) is

C2H5OH(l) is

H2O2(l) is

H2S(g) is

waterammonia

ozonemethane

glucose

ethanol

sucrosemethanol

hydrogen peroxidehydrogen sulfide

Hydrogen Compounds

- hydrogen compounds are those which contain a hydrogen at the beginning of the chemical formula and are dissolved in water (aqueous)

- Examples: HCl(aq) , HNO3(aq)

- hydrogen bonds covalently (shares electrons) to nonmetals to form a molecular compound which may be any state of matter, depending on the species being formed

- most hydrogen compounds are named as acids

- the only exceptions to this rule are the following pure substances

- HCl(g) – - HCl(g) – hydrogen chloride

- H2S(g) – - H2S(g) – hydrogen sulfide

- HCN(g) – - HCN(g) – hydrogen cyanide

- when hydrogen compounds dissolve in water they form acidic solutions

- HCl(g) is bubbled into water to form a solution called hydrochloric acid

Properties of Acids

- turns litmus indicator red

- tastes sour

- neutralizes bases

- conducts an electrical current

- pH is lower than 7

Naming Acids

Naming acids is easy if we follow this table:

hydrogen ___ide becomes hydro___ic acid

hydrogen ___ate becomes ________ic acid

hydrogen ___ite becomes ________ous acid

Examples: Name the following acids:

- HF(aq) – the normal name given to this chemical is hydrogen fluoride,

therefore, hydrogen fluoride becomes hydrofluoric acid

- HNO3(aq) – the normal name given to this chemical is hydrogen nitrate,

therefore, hydrogen nitrate becomes nitric acid

- HNO2(aq) – the normal name given to this chemical is hydrogen nitrite,

therefore, hydrogen nitrite becomes nitrous acid

We can read the table backwards to write out the chemical formula of a given acid name.

Example: Give the chemical formula for hydrosilicic acid.

- the acid name came from hydrogen silicate, therefore the formula must be H2SiO3(s)

- now change states to give the acid formula, H2SiO3(aq)

Classification of Acids

Binary Acids: Binary Acids: contain a hydrogen and one other kind of atom

Example: HCl(aq)

Oxo Acids:Oxo Acids: contain a hydrogen, an oxygen and one other kind of atom

Example: HNO3(aq)