Ionic, Metallic and Covalent Bonding

Writing and Naming Formulas

Chemical bond

force that holds two atoms together

opposites attract

the attraction between the positive nucleus of one atom and the negative electrons of another atom

Chemical bonds are formed by:

or by the attraction between positive and negative ions

Krypton

Iron in oxygen Potassium in water

Valence electrons

found in outermost energy level

electrons available to be lost, gained, or shared in the formation of chemical compounds

oct –

Octet Rule

Atoms tend to gain, lose, or share electrons in order to acquire a full set of eight valence electrons; stable noble gas configuration.

Three types of bonds:1. Ionic transfer of electrons between metal and nonmetal (or polyatomic ion)2. Metallic electron sea model; atoms of same metal 3. Covalent – sharing of electrons between nonmetals; may be same or different elements

atom, or a bonded group of atoms, that has a positive or negative charge

Ion

Ionic bond

electrostatic force that holds oppositely charged particles together

Positive ion formation

atom loses one or more valence electrons

cations

Write an electron configuration for sodium.

Write an electron configuration for neon.

What is the only difference in the electron configurations of these two elements?

Metals tend to lose electrons to form positive ions called cations.

Metals lose all valence electrons so that next energy level is full.

MagnesiumAluminumLithiumBariumPotassiumGallium

Write an electron dot notation for each metal:

Predict if each would lose or gain electrons when forming compounds:

MagnesiumAluminumLithiumBariumPotassiumGallium

How many electrons would each lose?

MagnesiumAluminumLithiumBariumPotassiumGallium

What cations would the following elements form? Write symbol and charge.

MagnesiumAluminumLithiumBariumPotassiumGallium

Use group number to predict charge of metal ion for representative elements only.

Group 1 1+

Group 2 2+

Group 13 3+

Transition metals

d block; filling inner energy levels

sometimes inner electrons take part in bonding

most form more than one common ion

Transition metals that form only one common ion:

silver Ag+

zinc Zn2+

Negative ion formation

atom gains one or more valence electrons

anion

Write an electron configuration for chlorine.

Write an electron configuration for argon.

What is the only difference in the electron configurations of these two elements?

Nonmetals tend to gain electrons to form negative ions called anions.

Nonmetals gain enough electrons to obtain full octet (8).

Write an electron dot notation for each nonmetal:

SulfurNitrogenIodinePhosphorusFluorineOxygen

Predict if each would lose or gain electrons when forming compounds:

SulfurNitrogenIodinePhosphorusFluorineOxygen

How many electrons would each gain?

SulfurNitrogenIodinePhosphorusFluorineOxygen

What anions would the following elements form?Write symbol and charge.

SulfurNitrogenIodinePhosphorusFluorineOxygen

Use group number to predict charge on nonmetals.

Group 18 0

Group 17 1-

Group 16 2-

Group 15 3-

Writing formulas for binary ionic compounds:

1. Write symbol and charge for cation and anion.

2. Use subscripts to show the ratio of ions.

Ex: lithium and oxygen

Cation always written first.

Ionic formulas, subscripts show simplest ratio.

Write formulas for the binary ionic compoundsformed between thefollowing elements:

a. potassium and iodine

b. magnesium and chlorine

c. sodium and sulfur

d. aluminum and nitrogen

e. aluminum and sulfur

Naming binary ionic compounds:

cation (metal) name of element; always written first

anion (nonmetal) name of element with an ‘ide’ ending

Name the binary ionic compounds indicated by the following formulas:

a. AgClb. ZnOc. CaBr2

d. SrF2

e. BaOf. CaCl2

Some metals form more than one common ion; most of the transition metals and tin and lead.

Transition metals – d electrons can take part in bonding

How form multiple ions?

Write noble gas notation for tin:

[Kr] 5s24d105p2

Sn2+ or Sn4+

Fe2+ Cl-

iron(II) chloride

Fe3+ Cl-

iron(III) chloride

The charge on the metal is written as a Roman numeral in the name of compound.

FeCl2

FeCl3

Transition metals that form only one common ion:

silver Ag+

zinc Zn2+

Metals that form only one common ion do not need Roman numeral.

NaBr sodium bromide

Write the formula and name for the compounds formedbetween the following ions(use Roman numerals):

a. Cu2+ and Br -

b. Fe2+ and O2-

c. Pb2+ and Cl-

d. Hg2+ and S2-

e. Sn2+ and F-

f. Fe3+ and O2-

Writing names with Romannumerals:

1. Determine total negative charge.

2. Total negative charge equals total positive charge.

3. Charge on one positive ion is Roman numeral.

Ionic compounds containingpolyatomic ions:

Write formulas as you would for binary ionic compounds;use parentheses if adding subscript to polyatomic ion.

Write formulas for the following compounds:

magnesium carbonate

magnesium hydroxide

Write formulas for the following ionic compounds:

a. lithium nitrateb. copper(II) sulfatec. sodium carbonated. calcium nitritee. potassium perchlorate

When naming compounds,do not change name ofpolyatomic ion.

Three types of bonds:1. Ionic transfer of electrons between metal and nonmetal (or polyatomic ion)2. Metallic electron sea model; atoms of same metal 3. Covalent – sharing of electrons between nonmetals; may be same or different elements

Why do atoms bond?

to obtain a full outer energy level; complete octet

to become more stable; lower potential energy

Electronegativity (EN)

indicates relative ability of an atom to attract electrons in a chemical bond

Metals

low EN; tend to give up electrons

Nonmetals

high EN; tend to gain electrons

What happens when two nonmetals, with similar EN, react?

Covalent bond

chemical bond that results from the sharing of valence electrons

generally formed between two nonmetals (same or different element)

electrons are attracted by the nuclei of two different atoms

Molecule

formed when two or more atoms bond covalently

Naming binary molecular compounds

1. First element; use entire element name.

2. Second element ends in –ide.

3. Prefixes are used to indicate the number of atoms of each element – the subscripts.

N2O4 dinitrogen tetroxide

If first element has one atom, mono omitted.

CO carbon monoxide

Name the followingmolecular compounds:

a. PF3

b. XeF4

c. As2O5

d. CCl4

Write formulas for thefollowing compounds:

a. carbon dioxideb. dinitrogen pentoxidec. silicon tetrafluoride

Ionic compounds

composed of large numbers of cations and anions; crystal lattice

formula unit – smallest whole number ratio of ions

Molecular compounds

composed of discrete (individual) molecules of covalently bonded atoms

molecular formulas do not need to be lowest ratio of atoms

C2H4

a substance that produces hydrogen ions (H+) when dissolved in water

Acid

molecular compound that reacts with water to form ions

1. binary acid – two elements; hydrogen and a nonmetal

name begins with prefix‘hydro’ and ends with ‘ic’

HCl hydrochloric acid

2. oxyacid – hydrogen, oxygen, and a nonmetal; many formed from polyatomic ions

if name of polyatomic ion ends with ‘ate’ , name of acid ends with ‘ic’

H2SO4 sulfuric acid

Binary acid

hydro _____ ic acid

Oxyacid

______ ic acid

Name the following acids:

H2CO3

HBr

Writing formulas for acids:

start with H+

determine charge on nonmetal ion or polyatomic ion

add subscripts if needed to make neutral compound

Write formulas for the following acids:

hydrofluoric acid

phosphoric acid

Electronegativity (EN)

indicates the relative ability of an atom to attract electrons in a chemical bond

Type of bond formed between two atoms depends on the difference in electronegativities (EN) of the atoms.

Difference in electronegativity (EN)

locate elements on periodic table

subtract values for EN

EN always positive

Ex: hydrogen and chlorine

EN = 3.16 – 2.20 = 0.96

Polar covalent bond

unequal sharing of electrons

one atom pulling electrons towards itself

Covalent bonds may be:

atom with higher EN value has a partial negative charge ()

atom with lower EN value has a partial positive charge ()

Ex: hydrogen and chlorine

EN = 3.16 – 2.20 = 0.96

Nonpolar covalent bond

electrons shared equally

no partial charges

Covalent bonds may be:

Most bonds are not completely ionic or covalent.

EN Bond Character

> 1.7 Ionic

0.4 – 1.7 polar covalent

< 0.4nonpolar covalent

Classify the following bonds as nonpolar- covalent, polar-covalent, or ionic. If bond is polar-covalent, assign partial charges.

C and H

H and Br

Cs and S

Properties of Compounds

depend on the strength of the attractive forces between particles

ions arranged in a regular repeating pattern called crystal lattice

Properties of ionic compounds

ions held together by strongionic bonds

Properties of ionic compounds

high melting and boiling points; much energy needed to separate ions

hard, rigid, brittle solids

Properties of ionic compounds

do not conduct electricity in solid state

aqueous solutions and liquid states are electrolytes - conduct electricity since ions are free to move

Properties of molecularcompounds

covalent bonds between atoms are strong, but attraction forces between molecules are weak

relatively weak forces of attraction between molecules

Intermolecular forces

also known as van der Waals forces

Properties of molecular compounds

relatively low melting and boiling points; many gases or liquids at room temperature

Properties of molecular compounds

do not conduct electricity when dissolved in water; except for acids

Metallic bond

outer energy levels of metal atoms overlap

valence electrons are shared by several atoms; delocalized (free to move)

electron sea model

attraction of a metallic cation for delocalized electrons

Metallic bond

Properties of metals

Properties of metals

moderately high melting points and high boiling points; most solids are room temperature

the more delocalized electrons a metal has, the greater its strength and hardness; groups 1 & 2 soft

Metals are malleable (hammered into thin sheets) and ductile (drawn into wires.)

good conductors of heat and electricity; electrons mobile

delocalized electrons interact with light, giving metals luster (shiny)

Three types of bonds:

1.Ionic – transfer of e-

metal and nonmetal

2. Metallic electron sea model; atoms of same metal

3. Covalent – sharing of e-

nonmetals

+ -

+

• Nonpolar Covalent - no charges

• Polar Covalent - partial charges

James Bond