Atoms that interact to form compounds are said to be chemically bonded.

Whether atoms interact depends almost entirely on the arrangement of their outer energy level (valence) electrons.

Only s and p sublevel electrons are thought of as valence electrons.

The maximum number of electrons, total, in the s and p sublevels is __

The maximum number of electrons, total, in the s and p sublevels is 8.

Electrons in the d and f sublevels are NEVER in the outer energy level of an atom.

Bonding - 7 min

Electrons are transferred between atoms.

One atom gains electrons while another atom loses electrons.

When this happens, the charges within each atom are no longer balanced...

the atoms have become ions - one with a positive charge, the other negative.

The force of attraction between these opposite charges hold the ions together in an ionic bond.

Ionization - the process of removing an electron from an atom to form an ion.

Ionization energy - the energy needed to remove an electron from an atom.

Electron affinity - the tendency of an atom to attract electrons.

Electron affinity determines the type of bond formed.

Metals generally have a low electron affinity.

Nonmetals generally have a high electron affinity.

Electrons are shared between atoms.

Atoms with similar electron affinities usually form covalent bonds.

Both atoms have an equal attraction for the electrons being shared.

The force of attraction between the nuclei and the shared electrons holds the atoms together in a covalent bond.

Chemical bonds are almost never totally ionic or totally covalent.

Bond types are often expressed as a percentage of each type of bond.

The closer two atoms are on the table, the more covalent their bond. CO and CO 2

The farther apart two atoms are on the table, the more ionic their bond. NaCl

100% Ionic FrF 100% Covalent F 2 ZnS 50% Each

The electrons in metals can be thought of as being property of all the atoms.

The positive nuclei are surrounded by a "sea" of electrons.

These loosely-held electrons are responsible for metals being good conductors of electricity.

A special type of bond between a hydrogen atom in a covalent molecule...

and an unshared electron in a nearby molecule.

Since a hydrogen atom is so small, it can get very close to other atoms -

causing electrons in those atoms to be attracted to it.

This is especially important with small, polar molecules like water.

It makes water a VERY GOOD solvent - especially with other polar substances.

Hydrogen bonding is responsible for water's very high specific heat capacity...

the ability to absorb large amounts of heat with little change in temperature...

and its relatively high boiling point.

two atoms of the same element covalently bonded together.

Seven elements exist in nature ONLY as diatomic molecules.

Know the seven diatomic molecules!!

Hydrogen - H 2 Nitrogen - N 2 Oxygen - O 2 Fluorine - F 2

Chlorine - Cl 2 Bromine - Br 2 Iodine - I 2

Begin with #7

There are 6 here in the shape of a 7

And 1 more here

A group of covalently bonded atoms that has an overall charge.

This group of atoms acts like a single ion when combining to form compounds.

The charge on a polyatomic ion is equal to its oxidation number.

Certain electron arrangements are more stable than others.

The most stable atoms have a full outer energy level.

Octet Rule - the maximum number of electrons in the outer energy level is 8.

Atoms will form compounds to reach eight electrons in their outer energy level.

Remember - hydrogen & helium, with only one energy level, can only hold 2 electrons.

Atoms with half-filled sublevels are somewhat stable.

A way of drawing the valence electrons. p p ps

The chemical symbol represents the center of an imaginary rectangle. p p ps

The symbol represents the atom's nucleus and all electrons, EXCEPT the valence electrons. p p ps

Each side of the imaginary rectangle represents an orbital within a sublevel of the outer energy level p p ps

Valence electrons in each orbital are represented by dots. p p ps

These arrows show the order in which electrons are added to the diagram - beginning with s. p p ps

The electron dot diagram for sodium looks like this - with one electron in the s orbital. Na

What would the electron dot diagram for magnesium look like?

What would the electron dot diagram for magnesium look like? Mg

What would the electron dot diagram for Aluminum look like?

What would the electron dot diagram for Aluminum look like? Al

What would the electron dot diagram for Silicon look like? Hint: Remember Hund's Rule

What would the electron dot diagram for Silicon look like? Si

What would the electron dot diagram for Phosphorus look like?

What would the electron dot diagram for Phosphorus look like? P

What can you say about the stability of an atom of phosphorus? P

An atom of phosphorus is somewhat stable because of the half-filled p sublevel. P

What would the electron dot diagram for Sulfur look like?

What would the electron dot diagram for Sulfur look like? S

What would the electron dot diagram for Chlorine look like?

What would the electron dot diagram for Chlorine look like? Cl

What would the electron dot diagram for Argon look like?

What would the electron dot diagram for Argon look like? Ar

What can you say about the stability of an atom of argon? Ar

An atom of argon is very stable because its outer energy level is full. Ar

What would the electron dot diagram for Copper look like?

What would the electron dot diagram for Copper look like? Cu

All transition metals have only two dots - Why? Cu

Notice the number of dots is the same as the group number.

Also notice that these dots are not placed exactly as we discussed.

Many college chem books stress symmetry of dots more than sublevels.

Since THIS class stresses the periodic table, sublevels are important.

What do you think of? O H H

Can these 3 atom diagrams O H H be combined into 1 molecule diagram?

A Water Molecule H 2 O O H H All atoms have a filled outer energy level.

This diagram not only shows properly filled energy levels, it correctly shows the shape of a water molecule!! O H H

When 10 cm 3 of acetone, C 3 H 6 O, are added to 10 cm 3 of distilled water, the combined volume is NOT 20 cm 3. Hypothesis:

Chemical Bonding Test Tomorrow

Whether atoms interact depends almost entirely on the arrangement of their _____ electrons.

Only ___ and ___ sublevel electrons can be valence electrons.

_____ bonds occur when electrons are transferred between atoms.

When atoms gain or loose electrons, they become ____.

The tendency of an atom to attract electrons is called ____.

Atoms with similar electron affinities usually form ____ bonds.

Bonding is usually expressed as a ___ of each type of bond.

There are ___ diatomic molecules.

Diatomic molecules must be written with a subscript of ___.

A group of covalently bonded atoms with an overall charge is called a ___.

In an electron dot diagram, dots represent ___.

The ___ states that the maximum number of electrons in the outer energy level is 8.

The valence electrons in the atoms of a sample of metal belong to ___.

The oxidation number of a polyatomic ion is equal to its ___.

Which of these atoms is most likely to form an ionic bond with sulfur? Lithium, nitrogen, aluminum

Which of these atoms has the highest electron affinity? Lithium, sodium, carbon

Which of these atoms will form a negative ion? iron, tin, chlorine

How many dots are in the electron dot diagram of arsenic?

How many dots are in the electron dot diagram of mercury?

Which of these atoms is the most stable? iron, nitrogen, chlorine

How many of these atoms do not conform to the octet rule? hydrogen, helium, argon

The formula for the phosphate ion is ___.

The formula for the ammonium ion is ___.

The formula for the sulfate ion is ___.

Chemical Bonding