IUPAC BOHR DIAGRAMS FOR ATOMS TYPES OF CHEMICAL BONDS MOLECULAR COMPOUNDS

◦ TYPES SIMPLE COVALENT

COMMON NAME

IONIC COMPOUNDS◦ SIMPLE IONIC◦ MULTIVALENT◦ POLYATOMIC/COMPLEX◦ HYDRATED IONIC

ACIDS

International Union of Pure and Applied Chemists

This is a global organization that sets the standards in chemistry.

One job of the IUPAC is to give compounds SYSTEMIC NAMES.

Bohr diagrams, also called ENERGY LEVEL DIAGRAMS, are a means of drawing atoms in a 2-D manner.

Keep in mind that atoms are actually 3-D, and there are more complex representations of atoms.

Bohr models always include the NUCLEUS and the ELECTRON ENERGY LEVELS of an atom.

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There are 3 types of SUBATOMIC PARTICLES found in the atom:

PROTONS (p+)◦ Positively charged particles with a significant mass◦ Atomic Number = Number of Protons

ELECTRONS (e-)◦ Negatively charged particles with an insignificant mass◦ Number of Electrons = Number of Protons

NEUTRONS (no)◦ Neutral particles with a significant mass◦ Number of neutrons = Atomic Mass – Atomic Number

NUCLEUS◦ Center of the atom, contains protons and neutrons

◦ The atomic mass is concentrated here

ELECTRON ENERGY LEVELS◦ Particular areas around the nucleus where electrons

are likely to be found

◦ Electrons DO NOT exist BETWEEN energy levels

◦ 3 LEVELS: FIRST LEVEL (Closest to Nucleus) 2 e-

SECOND LEVEL 8 e-

THIRD LEVEL (Outermost) 8 e-

VALENCE LEVEL◦ DEFINITION: Outermost energy level of an atom

◦ Electrons in this level are called VALENCE ELECTRONS

◦ Atoms with FULL valence shells are STABLE, meaning they will not bond with other atoms in normal conditions.

◦ The atoms of Group 18, the Noble Gases, have full valence levels.

◦ Atoms that do not have full electron energy levels are unstable and must GAIN, LOSE, or SHARE electrons to become stable.

ATOMIC NUMBER◦ Located in the top of each element box

on the periodic table.

◦ ATOMIC NUMBER = # OF PROTONS

ATOMIC MASS (MOLAR MASS)◦ Located in the bottom of each element box on the

periodic table.

◦ Round it off for calculations.

◦ ATOMIC MASS = # OF PROTONS + # OF NEUTRONS

EXAMPLE: DRAW BOHR DIAGRAMS FOR:

Li – lithium atom

◦ ATOMIC # = _____________

◦ ATOMIC MASS = _____________

◦ # p+ = ________________________

◦ # e- = ________________________

◦ # no = ________________________

EXAMPLE: DRAW BOHR DIAGRAMS FOR:

Ne – neon atom

◦ ATOMIC # = _____________

◦ ATOMIC MASS = _____________

◦ # p+ = ________________________

◦ # e- = ________________________

◦ # no = ________________________

EXAMPLE: DRAW BOHR DIAGRAMS FOR:

S – sulfur atom

◦ ATOMIC # = _____________

◦ ATOMIC MASS = _____________

◦ # p+ = ________________________

◦ # e- = ________________________

◦ # no = ________________________

IONS AS mentioned earlier, atoms other than the

NOBLE GASES are unstable, and need to GAIN, LOSE, or SHARE ELECTRONS to become more stable.

If they SHARE electrons, this forms a COVALENT BOND to another atom.

If they LOSE or GAIN electrons, atoms become IONS and form IONIC BONDS with other atoms.

Boron, carbon and silicon do not form ions.

OCTET RULE◦ Atoms that have an octet of valence electrons

are STABLE and UNREACTIVE.

Ions are charged atoms that have lost or gained electrons to achieve the valence configurations of a noble gas.

TWO TYPES:◦ CATIONS: POSITIVE ions that are formed from a LOSS of

electrons. It has more PROTONS than ELECTRONS and

therefore has a net POSITIVE charge. METALS form cations.

MEMORY TOOL: t in “cation” resembles a “+” sign EXAMPLE: lithium ion Li+ 1+ charge

◦ ANIONS:

NEGATIVE ions that are formed from a GAIN of electrons.

It has more ELECTRONS than PROTONS and therefore has a net NEGATIVE charge.

change the ending of the name of anions to -ide

NONMETALS form anions.

MEMORY TOOL: A Negative ION

EXAMPLE: fluoride ion F- 1- charge

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METALS◦ ATOMS of METALS will LOSE electrons to become CATIONS.◦ ATOMS with 1, 2, or 3 VALENCE electrons will LOSE these

electrons to form 1+, 2+, or 3+ ions respectively.

◦ GROUP 1 ATOMS – ALKALI 1 valence electrons(s) (will lose 1 to become stable) 1 + ion

◦ GROUP 2 ATOMS – ALKALINE EARTH 2 valence electrons(s) (will lose 2 to become stable) 2 + ion

◦ GROUP 13 ATOMS 3 valence electrons(s) (will lose 3 to become stable) 3 + ion

NONMETALS◦ ATOMS of NONMETALS will GAIN electrons to become ANIONS.◦ ATOMS with 5,6, or 7 VALENCE electrons will GAIN these electrons to form 3-,

2-, or 1- ions respectively.

◦ GROUP 15 ATOMS 5 valence electrons(s) (will gain 3 to become stable) 3 - ion

◦ GROUP 16 ATOMS 6 valence electrons(s) (will gain 2 to become stable) 2 - ion

◦ GROUP 17 ATOMS - HALOGENS 7 valence electrons(s) (will gain 1 to become stable) 1 - ion

◦ GROUP 18 ATOMS - NOBLE GASES FULL outer valence levels

Note that in BOHR DIAGRAMS for IONS, electron numbers have changed.

Here is a quick equation for calculating the number of electrons:

# e- = #p+ - charge

A sodium ATOM and a sodium ION

A chlorine ATOM and a chloride ION

CHEMICAL BONDS◦ DEFINITION:

A force of attraction between atoms.

◦ There are 2 TYPES of Chemical bonds

Covalent

Ionic

COVALENT BONDS◦ AKA: molecular bonds

◦ “co” – together/sharing , “valent” – outer shell

◦ DEFINITION: A SHARING of ELECTRONS between 2 atoms

BETWEEN a two or more NONMETALS

◦ Solutions of covalently bonded substances are NON-ELECTROLYTIC.

IONIC BOND◦ DEFINITION: A TRANSFER of ELECTRONS between two atoms

BETWEEN a METAL and a NONMETAL

◦ Solutions of ionic bonded substances are ELECTROLYTIC.

COMPOUNDS consist of atoms or ions of two or more elements bonded together.

Forms when 2 or more NONMETALS share electrons in COVALENT BONDS.

2 TYPES:◦ BINARY Molecular Compounds

◦ TRIVIAL NAME Molecular Compounds

Also called SIMPLE molecular compounds.

Binary Molecular Compounds use IUPAC prefixes:◦ We will write these prefixes in the following

table. Number Prefix

1 mono

2 di

3 tri

4 tetra

5 penta

6 hexa

7 hepta

8 octa

9 nona

10 deca

RULES:

1. Write NAMES of elements, with the 2nd

element ending in “-ide”.

2. Add PREFIXES to indicate HOW MANY ATOMS of each element.

3. Do NOT use the prefix “mono” for the 1st

element, only with the 2nd element.

N2O4 ________________________

P2O5 ________________________

CCl4 ________________________

RULES:

1. Write ELEMENT SYMBOLS for each element in the compound.

2. Use the PREFIX in the name to determine NUMBER OF ATOMS, and write that number as a SUBSCRIPT next to the symbol (no subscript for 1 atom).

carbon monoxide ____________

triphosphorus pentabromide ____________

sulfur hexafluoride ____________

Also called COMMON NAME molecular compounds.

There are SOME molecular compounds that go by their COMMON NAMES, and we must memorize these names.

FORMULA TRIVIAL/COMMON NAME

H2O water

H2O2 hydrogen peroxide

NH3 ammonia

CH4 methane

H2S hydrogen sulfide

C12H22O11 sucrose

Form when at least 1 METAL AND 1 NONMETAL transfer electrons in an IONIC BOND.

Metals will become CATIONS and LOSEelectrons and nonmetals will become ANIONS and GAIN electrons.

These ions, with opposite charges, attract and form IONIC BONDS.

Unlike covalent bonds, these bonds are not “ACTUAL BONDS,” but forces of attraction between oppositely charged ions.

They stay together in a CRYSTAL LATTICE.

Example: NaCl (Draw on your sheet)

Cl- Cl-

Cl-Cl-

Cl-Cl-

Cl-

Na+

Na+Na+Na+ Na+

Na+Na+

Cations are surrounded by anions and vice versaAlso refer to Figure 4, p. 189

Example: NaCl

3 TYPES:◦ Binary Ionic Compounds

SIMPLE

MULTIVALENT

◦ Polyatomic Ionic Compounds

◦ Hydrated Ionic Compounds

“Binary”

Only 2 types of ions involved.

SIMPLE IONIC COMPOUNDS

◦ Simple ionic compounds are composed of a metal ion (+) and a nonmetal ion(-).

GIVEN FORMULA, WRITE NAME

◦ RULES:

1. Write the name of the CATION before the ANION (Be positive before being negative )

2. Change the ending of the ANION name to “-ide”

3. Do not use CAPITALS, Do not use PREFIXES!

EXAMPLE:◦ MgBr2 _________________________________

◦ KCl _________________________________

◦ Na2S _________________________________

◦ Mg3P2 _________________________________

◦ Ba3N2 _________________________________

WHAT’S WRONG WITH THE FOLLOWING NAMES FOR BaS?◦ barium sulfur ____________________________

◦ Barium Sulfide ____________________________

◦ barium sulfuride ____________________________

GIVEN NAME, WRITE FORMULA◦ RULES:

1. Write element symbols.

2. Look up the ION CHARGE on the periodic table.

3. Use the “crossover” method to determine the numbers of each ion in the compound.

4. Ion ratios are always in the lowest common multiple.

5. Ion charges must add up to “zero” overall.

EXAMPLE: sodium bromide _____________________

barium iodide ___________________

EXAMPLE: magnesium oxide _____________________

aluminum oxide ___________________