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CHEMISTRY REVISION SHEETS
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
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.
Other pages in this set
Here's a taster:
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 of the atom is far away from the nucleus which means that it's EASY TO GET RID OF.…read more
Here's a taster:
Most Noble gases are used in everyday life too Neon is used in Tacky shop signs. They are cheap to
run because they don't take much electricity and they give a bright RED light when it's NEON. Noble
gases are even used in the famous helium-neon laser and the more powerful Argon laser. Helium is
used in airships and party balloons because it is lighter than air. It is used instead of hydrogen due to
its unreactability.…read more