ELEMENTS, COMPOUNDS AND MIXTURES

*ATOMS
Elements are made up of tiny particles called atoms. The atoms of one element are not same as the atoms of another element. To show one atom of an element, chemists use its chemical symbols.
Eg : To show ONE atom of hydrogen, chemists write "H" since the chemical symbol for hydrogen is "H". Atoms are joined chemically to form elements however there are some elements which defy this rule. The elements are Helium, Neon, Argon, Krypton, Xenon and Radon are the only elements that exist as individual atoms which means that their atoms are not chemically joined. They are called MONATOMIC ELEMENTS.
Metals exist asa atoms but large numbers of their atoms are arranged in a special way to form giant structures. Most non-metals exist as molecules.

*MOLECULES
A molecule is a group of tow or more atoms chemically joined together.
Molecules formed by the combination of two atoms is called "diatomic molecules" where as molecules with three atoms are called triatomic molecules and molecules formed by four or more atoms is called polyatomic molecules.

ELEMENTS, COMPOUNDS AND MIXTURES

Hi everyone. As promised I am posting the notes. I won't say my notes are 100% accurate and I am not sure if blogspot.com allows you to comment. If it does, please feel free to comment below your recommended websites for chemistry notes or feedback to me. Thank you.

ELEMENTS, COMPOUNDS AND MIXTURES

We would generally classify MATTER as SOLID, LIQUID and GAS. However when it comes to this chapter, we can classify them as Elements, Compounds and Mixtures. There are 116 elements known to be existing on Earth currently and 92 of them are naturally found while 24 of them are man-made. 

*ELEMENTS

#MUST MEMORIZE

>An element is a pure substance that cannot be broken down into any simpler substances by chemical processes or by electricity.

 l___>An example would be COPPER, it cannot be broken down into any simpler substances thus it is an element. Sugar can be broken down into carbon by heating it so it is not an element. Water can also be heated to be broken down to elements hydrogen and oxygen. Carbon, hydrogen and oxygen are elements because they cannot be broken down any further into simpler substances. 

>Chemical symbols are used to express elements. Eg: calcium = Ca, carbon = c, hydrogen=H, iron = Fe

>Elements can be classified into metals and non-metals.

>Elements that have properties of both the metals and the non-metals. They are called metalloids.

>THE TABLE OF PHYSICAL PROPERTIES FOR METALS AND NON-METALS

METALS                                                                                                                        NON-METALS      
1) Shiny Appearance ( Lustrous )                                 Dull Appearance if solid ( Non-Lustrous )
2) Solids at room temperature pressure                      Either gases, volatile liquids or solids with low melting points at r.t.p.( except for carbon )
3) Malleable                                                                     Brittel if solid
4) Sonorous ( Make a ringing sound when struck )   Do not have this ability
5) Ductile ( Can be drawn into wires)                          Do not have this ability
6) High melting and boiling points                               Low melting and boiling points 
7) Good conductors of heat                                           Poor conductors of heat
8) Good conductors of electricity in all                         Poor conductors of electricity 
states of matter

AS usual in Science, there are some elements that define the properties as stated in the table above. 

The Periodic Table

http://www.ptable.com/
^That my friend, is a screenshot. Do go to the websites and play around to get familiar with it. It is a very good websites. Will post more notes on this later. :)