review of atomic model

Review of Atomic Model

Elements are pure substances containing one type of atom – found on the Periodic Table.

The atom is the smallest part that retains all the properties of that element.

protons (p+) neutrons (no) electrons (e-)

Charge

Mass

Location

+1.6 x 10-19 C 0 -1.6 x 10-19 C

1.67 x 10-24 g 1.67 x 10-24 g 9.11 x 10-28 g

Nucleus Nucleus Orbit clouds

Octet rule: atoms react to acquire a full outer shell:

•Give away an e- to another atom.•Take an e- from another atom.•Share an e- with another atom.

Ionic bond

Covalent bond

An ION is an atom that has lost or gained an electron.

H : neutral atom

H+ : positive cation

H- : negative anion

+1

+2 -3 -2 -1+3 +4/-4

Remember: The number of the column is equal to the valence electron number. Know that and you figure out the number of electrons lost or gained – the ionic charge

Ionic

NaCl

A compound has different characteristic properties than the atoms which form it.

Covalent

HCl

Ionic Compounds

Contain a METAL and a NON-METAL atom.

Formed by TRANSFERING valence electrons to fill outer shell – octet rule.

A formula unit is the smallest unit of an ionic compound.

Metal + Non-metal = ionic bonding

Writing Rule 1: Write the symbol of the metallic element first.

Be Cl

Rule 2: Place the combining capacity of one element as a subscript of the other element.

Beryllium combines with Chlorine

+ -12

Rule 3: Leave subscripts with a value of 1 out.

Be Cl2 1

Two Naming rules: 1.Write the full name of the metal ion first. 2.Name the non-metal ion dropping the last part of the name and adding the suffix “ide”.

berylliumchloride

Rule 4: Reduce the subscripts if possible.

Mg S

Magnesium combines with Sulfur

Mg S + -22

magnesium sulphide

Transition metals

Transition metals can give away different numbers of electrons.

To avoid confusion:

Brackets are used to show how many electrons the Transition metal is giving away.

Iron (III) chlorideIron (II) chloride

Fe Cl + -12

FeCl2

Fe Cl + -13

FeCl3

Write the name of the ionic compound:

PbO

Pb O+ -

1 2

lead oxide(IV)

+4 -2Remember: Always look at the anion to

see if it has been reduced. If it has, so has the metal.

Polyatomic Ions (poly = many)

Groups of covalently bonded atoms that act as ions in ionic bonding.

Polyatomic ions function as one unit with one charge – lose or gain electrons.

NEVER change the subscripts of polyatomic ions.

Al(C2H3O2)3

Write the name of the ionic compound:

Al(C2H3O2)

Al C2H3O2

+ - 1

3

aluminum acetate

nickel (II) nitrate

MgSO4

potassium permanganate

Fe(OH)3

calcium acetate

Ag2CrO4

lead (II) carbonate

Sn(SO4)2

sodium hydrogen phosphate

NH4NO2

1. Ni(NO3)2

2. magnesium sulfate

3. KMnO4

4. iron (III) hydroxide

5. Ca(C2H3O2)2

6. silver chromate

7. PbCO3

8. tin (IV) sulfate

9. Na2HPO4

10.ammonium nitrite

Covalent Compound

Contain two or more NON-METAL atoms.

Formed by SHARING valence electrons to fill outer shell – octet rule.

A molecule is the smallest unit of a covalent compound.

Non-metal + Non-metal = covalent bonding

Prefix Number of Atoms

mono 1di 2tri 3

tetra 4penta 5hexa 6hepta 7octa 8nona 9deca 10

Step 1: first non-metal is named with a prefix to show the number of atoms.

We do not use “mono” for the first non-metal.

nitrogen oxide

N O

Step 2: second non-metal is named with a prefix AND with the “ide” ending.

di

2 4

tetradinitrogen tetroxide

PrefixNumber of

Atoms

mono 1

di 2

tri 3

tetra 4

penta 5

hexa 6

Writing formulas

Step 1: Write the symbol of each element.

Step 2: Use a subscript to show the number of each type of atom given by the prefix.

Do not reduce covalent formulas.

phosphorus oxide

P O di

2 5

pentaPrefix

Number of Atoms

mono 1

di 2

tri 3

tetra 4

penta 5

hexa 6

Does it have a metal?

NO (covalent)YES (ionic) Is it a transition? • NO charges

• NO criss-cross• Use prefixs• Ends in “ide”

•Find charges•Reverse Criss-cross•Use Brackets•Ends in “ide”

•Find charges•Criss-cross•Ends in “ide”

MgCl2magnesium

chloride

CuCl2copper (II) chloride

OCl2oxygen

dichloride

NO YES

Polyatomic•Find charges•Reverse Criss-cross•Don’t change ending

Fe(NO3)2

iron (II) nitrate

• Many reactions are similar

• Chemists have classified 5 types of reactions

BIG PICTURE IDEA:

• If you know the reactants - you can guess the type of reaction AND predict the products

Synthesis A + B C

Decomposition C A + B

Single replacement A + BC B + AC

Double replacement AC + BD AD + BC

Carbon Combustion CxHy + O2 CO2 + H2O

Diatomic Elements: Elements that are most commonly found in a covalent bond with itself.

I Have No Bright Or Clever Friends

I2 H2 N2 Br2 O2 Cl2 F2

• Explain the difference between isotope and radioisotope

• Explain average atomic mass using isotopes and their relative abundance

Additional KEY Terms

Radioactive decay Half-life

The atomic number (Z) is the number of protons in the nucleus of an atom - identifies an element.

The atomic mass (A) is the number of protons plus the number of neutrons.

Isotopes: Atoms with the but a different number of neutrons.

Atomic mass is actually an average of isotopes of an element based on relative abundance in nature.

same number of protons

Deuterium Atomic Mass = 2

Atomic Number = 1

Hydrogen Atomic Mass = 1

Atomic Number = 1

Mass spectrometer determines the mass of individual atoms or isotopes.

Sends atoms through a magnetic field which bends their paths.

The heavier the atom – the less it bends.

Potassium isotopes:

1. 19 protons and 20 neutrons - mass number of 39(potassium-39 39K)

2. 19 protons and 21 neutrons - mass number of 40 (potassium-40 40K)

3. 19 protons and 22 neutrons - mass number of 41 (potassium-41 41K)

Magnesium exists as three isotopes in the world:

78.99% is 24Mg (23.985 μ)10.00% is 25Mg (24.986 μ)11.01% is 26Mg (25.982 μ)

(0.7899)(23.985 μ) = 18.95 μ

(0.1000)(24.986 μ) = 2.499 μ

(0.1101)(25.982 μ) = 2.861 μ

= 24.31 μ +

Calculate the average atomic mass of magnesium:

helium 5He 6He

The nucleus of some isotopes are unstable and break apart over time - radioactivity.

Radioisotopes - unstable nuclei releasing energy and/or particles.

Release of energy is called radioactive decay.

Atom may be converted into another isotope or a completely different element.

Half-life - amount of time it takes for half the radioisotope to be converted into another particle.

Many different types of decay: alpha decay, beta decay, gamma decay

CAN YOU / HAVE YOU?

• Explain the difference between isotope and radioisotope

• Explain average atomic mass using isotopes and their relative abundance

Additional KEY Terms

Radioactive decay Half-life