Periodic Table Flashcards
What are atoms?
Atoms are the basic building blocks of all materials.
Element
An element is a substance made up of only one type of atom.
Symbol
Each element has a symbol.
Eg. H is the symbol for Hydrogen.
Molecules
A molecule is formed when two or more atoms join (bond) together chemically.
Compounds
When a molecule is made up of two or more different types of elements chemically combined, we call it a compound.
Hydrogen gas (H2) and oxygen gas (O2) are not compounds because each is composed of one element.
ALL COMPOUNDS ARE NON-ELEMENTS.
What is the Periodic Table?
The periodic table is considered to be one of the most important tools of the chemist. It shows a list of all the 118 elements.
The modern Periodic Table
The modern periodic table has no gaps in it. It has:
-Vertical columns, called groups, in which the element with similar physical and chemical properties (behaviours) are grouped together.
-Horizontal rows, called periods which are in order of increasing proton number.
Group 2 - The Alkaline Earth Metals.
Elements in this group include:
-Beryllium (Be)
-Magnesium (Mg)
-Calcium (Ca)
All elements in this group have 2 electrons in their outer shell.
Group 7 - The Halogens
The elements in group 7 have seven electrons in their atoms outer shell.
Eg. Fluorine & Chlorine
Group 8 (group 0) - The noble gases
The elements in group 8 are all gases and have full outer shells of electrons in their atoms. Theses are stable atoms.
Eg. Helium, Neon, Argon.
What are ions?
When atoms lose or gain electrons they become charged particles and are called ions.
How are chemical bonds formed?
A compound forms when two different elements chemically combine.
Ionic Bonding
Ionic bonding produces a compound that is formed from a metal and a non-metal and is made up of ions. This occurs when one atom looses electrons and another atom gains electrons.
Combing metals and non-metals
When a metal and non metal are combined, the resultant compound is called after the name of the metal followed by the name of the non metal, with its ending changed to ‘-ide’.
Eg. Sodium + chlorine = sodium chloride.
