With your pair define the following words: Elements, compounds, mixtures and

molecules Leave 3 lines below each definition

Gallery walk: you have 5 minutes to see what your classmates have written and add anything you like onto your definitions

Pair work

At the center of each atom is the nucleus. The nucleus is a cluster of particles called protons and neutrons. Protons have a plus (+) charge, and neutrons are neutral (that is, they don't have a charge).

Most of the atom is empty space! Electrons have a minus (-) charge, and so there are enough electrons to balance out the (+) protons.

Electrons are so light that they really don't count towards the total weight of the atom.

Atoms, elements and compounds

Electrons in the atoms, cannot move anyway they wish. They are restricted to levels (n).

The first level can hold only two electrons. (ex: H)

The second and third level can hold eight electrons (ex: C)

Hydrogen

Carbon

Atomic structure

1n1p

Atomic structure

16n16p

17n17p

Atomic structure – Valence electrons

5p5n

The columns in the Period Table indicate the amount of Valence electrons. Those are the ones found in the outermost level.

These electrons have a very special job... They form bonds!!!!

Atomic structure

http://www.webelements.com/

1. Search for the elements (Sodium, Calcium, Aluminium, Carbon, Phosphorus, Oxygen, Fluorine and Neon) in the periodic table

2. Create a table to include the following information:

1. Element2. Symbol3. Amount of protons, neutrons and electrons4. Draw the atomic structure for each of these atoms5. Determine the amount of Valence electrons in each

of them

Atomic structure exercise

Ionic bonds

Ionic bonds happen when one atom gives at least one electron to another atom.

The atom that gets an extra electron ends up with a (-) charge and is called an anion. The atom that gives away an electron ends up with a (+) charge and is called a cation.

Now, those (+) and (-) charges have a strong attraction to each other - they sit next to each other and refuse to move.

Covalent bonds

Covalent bonds happen when two atoms share electrons - kind of like 2 atoms holding hands.

Sometimes molecules share more than one pair of electrons. If two pairs of electrons are shared then a double bond is formed, and if three pairs are shared then a triple bond is formed. It is not possible to form a "quadruple" bond!

Compounds

Compounds

.

Ionic bonds Covalent bonds

Compounds

NaF KCl CaO CaS MgCl2

HCl O2

H2O CO2

NH3

CH4

Exercises

Classification of matter

States of matter

Heating curves