Chemistry Basic P1 Revision Edexel

Atoms are structured like so:

The nucleus has most of the weight but is the smallest part of the atom itself. It contains the NEUTRONS and the PROTONS. The nucleus has an overall charge of +1 because the PROTONS are +1 and the NEUTRONS are +0

The ELECTRONS are situated in the orbiting rings AROUND the nucleus. They take up a lot of space but do not weigh very much at all… They have a charge of -1. The rings can only hold a certain number of electrons in them. The order goes 2, 8 etc.

Particle

Relative Mass

Relative Charge

Proton

1

+1

Neutron

1

0

Electron

1/2000

-1

The ATOMIC NUMBER is how many protons there are in the element. The Periodic Table is arranged in accordance to ATOMIC NUMBER. The ATOMIC NUMBER is also the same as the number of ELECTRONS. The RELATIVE ATOMIC MASS of an element is the total number of protons and neutrons inside the atom. So the number of NEUTRONS in the atom = RELATIVE ATOMIC MASS - ATOMIC NUMBER.

For Example:       RAM                   --->           16                    (OXYGEN ATOM)

             ATOMIC NUMBER                   --->      8

Lots of the time, atoms in GAS STATE float around in PAIRS making them DIATOMIC for example, OXYGEN is normally found in the air as O2 because it has 2 atoms of oxygen floating around joined together.                                                   

The Periodic Table:

Scientists only began wanting to find patterns in the elements in the 1800s so DMITRI MENDELEEV put together his periodic table which was the FIRST periodic table EVER. His periodic table placed elements with similar chemical properties in the same vertical groups but he found that he had to leave gaps to make it work. This was clever – he predicted more elements were going to be discovered later in history. Now, after new elements have been found, scientists have been refining MENDELEEV’s table even today.

<--- This is the modern periodic table. It’s laid out so elements with SIMILAR PROPERTIES are arranged together in COLUMNS. These COLUMNS are called GROUPS. Elements in the same group are similar in reactability and what happens when they react with a certain something for example, water… Normally, the RAM NUMBER is the TOP number of the element and the SMALLER, LOWER number is the ATOMIC NUMBER.

Elements and Groups that you NEED to know:

Group 1 Elements – The ALKALI METALS:

Group 1 elements (Lithium, Sodium, Potassium, Rubidium, Francium, Caesium) are also known as the ALKALI METALS react VIGOROUSLY in WATER. This reaction forms an ALKALINE solution with the water (would make UI blue).

The reason they react so VIGOROUSLY with WATER is because the LINGERING ELECTRON in the OUTER SHELL…