Bonding

Important Vocab

Affinity Energy - how much energy an atom gives off when it takes in an electron.

Lattice Energy - how much energy is given off after affinity energy.

Chemical Bonds

Chemical bond - force of attraction that holds atoms together. In this case, an electrostatic attraction.

Lithium gives its electron to fluorine, so they are both stable with completely full energy levels.

Why?

1. become stable by making an octet

2. lower overall energy of the system.

When lithium gives its electron off, it gains some energy. That energy is called the ionisation energy (520 kj/mol), and it results in lithium being positively charged.

Fluorine gets two drops in energy.

Dot Structures

Sodium has one dot because it has one valence electron. Fluorine has seven dots because it has seven valence electrons. After giving up an electron, sodium has none, and fluorine has 8 dots. There's also a bracket around the stable element, as it reacts similarly to a noble gas. You need to make sure that eletrons all add up to 8.

Magnesium has a charge of 2+ and chloride has a 1- charge. Therefore, you need 1 magnesium and two chlorides to make it balanced.

Aluminum wants a 3+ charge, and Oxygen wants a 2- charge. Al2O3.

Ca+2 & NO3 -2 ➝ Ca + (NO3)2

Aluminum Chromate ➝ Al2 (CrO4 2-)3

Cutoff! Day 1 above, day 2 below

Physical Properties

• White

• Crystalline

• Solid

• Brittle

• Hard (hehehehehe)

• High Melting Point

• (Most are) Soluble in Water

  • Electrolytes

Solvation

When a water attacks an ionic compound, it needs to attack in just the right way (charge-wise).

The oxygen is charged negatively, and the hydrogens are charged positively. So, if water is bonding to an ionic compound, the oxygen will go towards the non-metal, and the hydrogen will go towards the metal. (Or that's what I got.)

Electrolytes and Its Uses

• Body chemistry (that's the reason Gatorade advertises it)

• Food preservation (putting salts)

• Colorants (they produce colours that can be used as dyes. Iron oxide is red, and cobalt is blue, for example)

• Melting agent (they put salt on the roads to help melt it because saltwater freezes at a lower temperature than regular water. this won't help if you're in Antarctica, tho)

Isolation - How to Get Salts

• Salt deposits (yes, you can mine salt)

• Evaporation (you let the saltwater evaporate, and then salt appears! so cool!)

• Precipitation reactions (if you mix stuff together, there's sometimes a precipitate. those are salts)

• Reverse osmosis (how they filter water. if you're filtering water, you could definitely take the stuff that's filtered out and use it)

Compounds

Binary compound - two different elements (CaCl2 - calcium chloride - two different elements)

Ternary compound - three different elements (NaNO3 - sodium nitrate - three different elements)

monatomic ion - Cl, O

polyatomic ion - NO3, Cr2O7

Formula unit - a compound that's reduced down to its basic formula (Magnesium Oxide - Mg 2+ & O 2- ➝ Mg2O2 ➝ MgO)

Lattice Energy

Energy released when you combine two atoms.

Na+Cl releases 749 KJ/mol

The more energy given off, the stronger the ionic bond.

Two factors:

1. Charge of the ions: more ionic charges ➝ stronger bond & more lattice energy given off

2. Size of ions - if they can pack tighter together, they can release more energy: the smaller the ion, the more lattice energy given off

Covalent Bonds

Covalent bond - force of attraction between 2 atoms sharing electrons

This thing forms molecules

Molecules are individual units, unlike ions.

A non-metal is bonded with a non-metal to form a molecule.

Types of Bonds

Single bond - one electron is shared

X:X or X-X

Double bond - two electrons are shared

X::X or X=X

Triple bond - three electrons are shared

X:::X or X=X

Examples

C-C - carbon bonded to carbon

N-H - nitrogen bonded to hydrogen

O-P - oxygen bonded to phosphorous

S-H - sulfur bonded to hydrogen

H-O - hydrogen bonded to oxygen

Prefixes

NO2 - Nitrogen Dioxide

CCl4 - Carbon Tetrachloride

CO - Carbon Monoxide

H2O - Dihydrogen Monoxide

Molecular Dot Structures

Rules:

1. Do an electron inventory

   1. electrons in focus being valence electrons

2. The first atom in the formula goes in middle

   1. Carbon Dioxide: O=C=O

3. Start with all single bonds (before using double and triple bonds)

4. All atoms need 4 pairs of electrons (8 electrons, octet)

Examples

OH2:

Oxygen has 6 electrons, Hydrogen has 1 electron

Oxygen will take the 2 electrons from the collective hydrogen

(non-bonding electron pairs are shown by dots. you only show them once.)

H-::O::-H

Carbon Tetrafluoride - CF4

Carbon has 4 electrons, Fluoride has 7 electrons (meaning 28 electrons + 4 electrons = 32 electrons)

CH2O - formaldahyde

Carbon has 4 electrons, Hydrogen has 1 (meaning two), Oxygen has 6 electrons

12 electrons total

..

H-C-:O:

|

H

N2 - diatomic nitrogen

Nitrogen has 5 electrons each

:N=N:

Carbonate ion - CO3 2-

(MAKE SURE TO ADD IN 2 ADDITIONAL ELECTRONS FOR 2-, AND SO ON)

:O::-:C:=:O:

|

:O::

Properties of Molecular Substances

• Can be a liquid, solid, or gas

• Low melting point/boiling point (in general. you can have a much bigger variety.)

• Can be white solids (like sugar), can look like ionic compounds, but isn't always

• Soluble in water (sometimes. sugar and alcohol yes, oils no)

• ALL are non-electrolytes. They won't conduct electricity.

• Some are volatile. Some can emit odours.

• Have a range of viscosities.

• Unlike ionic compounds, some can catch on fire (flammable).