- Created by: Alice
- Created on: 13-01-12 18:13
The Fundamental Ideas: Atoms overview.
Atoms contain a nucleus which is surrounded by electrons.
The nucleus contains protons and neutrons.
Protons and electrons each have a relative electrical charge.
Protons are charged by +1. Remember that this is called a positive charge.
Electrons are charged by -1. Remember that this is called a negative charge.
Neutrons are neutral. This means their charge is zero.
The Fundamental Ideas: The Periodic Table.
The Periodic Table contains the 100 known elements.
It is made up of non-metals and metals.
Each column is called a group and each row is called a period.
Elements in the same group in the periodic table have similar chemical properties.
This is because their atoms have the same number of electrons in the highest occupied energy level. (More on this on Slide 4!)
Group 1 elements are reactive metals called the alkali metals.
Group 0 elements are unreactive non-metals called the noble gases.
The Fundamental Ideas: Atomic Number and Mass Numb
Every element is represented in the Periodic Table by a symbol with an Atomic Number and a Mass Number. Here's the breakdown:
The Atomic Number is the amount of protons in one atom of the element.
The Mass Number is the total of the protons and neutrons in one atom of the element.
We can now find the protons, neutrons and electrons in an atom of the element.
Atomic Number = Number of Protons.
Mass Number - Atomic Number = Number of Neutrons.
In all atoms, the amount of protons is equal to the amount of electrons. Therefore: Atomic Number = Number of Electrons.
If the Atomic Number of an element was 10 and the Mass Number was 18:
Protons = 10, Electrons = 10, Neutrons = 8.
The Fundamental Ideas: Electronic Structure.
Atoms are made up of different shells which electrons are arranged in.
The shells can be called energy levels. The highest energy level is the outer shell.
The electronic structure is when we write down the numbers of the electrons in each energy level.There are rules about the electrons in each energy level:
The first and lowest energy level can contain up to 2 electrons.
The second energy level can contain up to 8 electrons.
The third energy level can also contain up to 8 electrons.
The Fundamental Ideas: Forming Bonds.
If a metal reacts with a non-metal, the atoms bond by transferring electrons.
If a non-metal reacts with a non-metal, the atoms bond by sharing electrons.
The atoms then become ions/molecules which are charged. Metals which bond give positively charged ions, non-metal molecules are negatively charged.
Opposite charges attract. The charges always cancel each other out in a compound of non-metal and metal.
In a compound of non-metal and metal atoms, there are strong bonds between the atoms. These strong bonds are the chemical bonds that from called ionic bonds.
The outer shells of two non-metal atoms that are reacting overlap and the two atoms share electrons.
Each pair of shared electrons forms a chemical bond between the two atoms. The bonds are covalent. This makes them a molecule.
The Fundamental Ideas: Balancing Equations.
Word equations are better than symbol equations as they can become complicated and they do not specify the amounts of chemicals used.
Mass of Products = Mass of Reactants.
When balancing an equation, count the atoms on both sides.
Make sure there is the same amount on each side.
If one side is not equal, add a number in front of it.
H2 + 02 = 2H20