Elements, Compounds, Mixtures

Hello everyone. Today, I am going to update you guys on my science ace assignment for term 3. I did a study on elements, compounds and mixtures and I will now share what I have researched with all of you.

First of all,

What is an ELEMENT???

• A substance than cannot be broken down into two or more substances by chemical methods
  

• Example: Helium, Oxygen, Iron, Copper, Iodine, etc.

So now that you know what an element is, I will show you something called the "Periodic table" where all elements are classified there.

How the periodic table is organised:

You might think that the elements in the table above are put in random. Actually, there are placed according to their properties. There are TWO main groups: Metals and non metals.
Each vertical coloumn is called a group while each horizontal row is called a period. Elements in the same group have similar chemical properties

Group properties in the periodic table:

• Group 1 elements are also called "The Alkali Metals". Elements in this group are the most reactive metals in the periodic table. The elements are also shiny, silvery solids and are all easily cut with a knife. They have low densities and melting points too. Examples of them would be : Lithium and rubidium.
  
• Group VII Elements are also called "The Halogens". It is a group of similar non metals that are reactive with most metals to form salts. They have low melting points and boiling points. Examples of them would be fluorine and chlorine.
  
• Group 0 elements are also called "The Noble Gases. Elements in this group are the least reactive elements in the periodic table and are all colourless gases which have very low melting and boiling points.
  

Facts about elements:

1)There are 116 known elements up to date, 92 found on earth and 24 made by scientists.
2)Symbols for elements usually have letters from their english names.
3)The most abundant element on earth is oxygen.

What are ELEMENTS MADE UP OF???

They are made up of Atoms and Molecules.
*Atoms are the smallest unit of an element and has the properties of the element
**Molecules are a group of two or more atoms that are chemically joined together

Examples of elements (METALS):
Aluminium:
Symbol: Al
Atomic Number: 13
Physical state: Solid
Uses: Cooking foil, drink cans, aeroplane parts
9% of all elements
not soluble in water under normal conditions
Most abundant metal in earth’s crust
3rd most abundant metal in earth
low density
soft, durable & malleable metal

Calcium:
Symbol: Ca
Physical state: Solid
Atomic number: 20
5th most abundant element in Earth’s crust
Essential for living organisms
Used in mineralisation of bones and shells
Most abundant metal in animals
3% of all elements
Group: 2
Density: roughly 1.55 g cm-3
Melting point: 1548 F=842 degrees celcius

Copper:
Symbol: Cu
Physical state: solid
Atomic number: 29
Ductile metal
Very high heat and electrical conductivity
Group: 11
Uses: wires, coins, switches, pots, pans, window, door frames, pipes, building material
Pure copper is soft and malleable

Iron :
Symbol: Fe
Physical state: solid
Atomic number: 26
4 % of all elements in earth’s crust
Group: 8
Period:4
4th most common element in the Earth’s crust
Used to make cutlery
Boiling point: 5182 F
Melting point: 2800 F

Magnesium :
Symbol: Mg
Physical state: Solid
Atomic number: 12
2% of all elements in the earth’s crust
8th most abundant element in earth’s crust
High solubility in water
11th most abundant element in a human body
Strong, silvery white, light weight metal
Highly flammable
Used to make milk of magnesia, which is used to relieve acid indigestion
Used for fireworks and distress flares

Mercury :
Symbol: Hg
Physical state: liquid
Atomic number: 80
One of five metallic chemical elements that are liquid at room temperature
Melting point: -38.83 degrees celcius
Boiling point: 356.73 degrees celcius
Uses: fluorescent lamps, thermometers, dental fillings, barometers, manometers
Heavy silvery white metal
Poor conductor of heat (compared to other metals)

Potassium :
Symbol: K
Physical state: solid
Atomic number: 19
2% of all elements in earth’s crust
Soft, silvery white metal
Very reactive with water
Found dissolved in seawater
7th most abundant element in earth’s crust
Boiling point: 1398 F
Melting point: 146.08 F
2nd least dense metal

Sodium
Symbol: Na
Physical state: solid
Atomic number: 11
3% of elements in earth’s crust
Soft, silvery white metal
Group: 1
Essential element for all animal life & for some plants species
At room temperature, it is soft to be cut with a knife
Reacts exothermically (a chemical reaction that releases energy in the form of heat) with water

Zinc:
Symbol: Zn
Physical state: solid
Atomic number: 30
Group: 12
24th most abundant element in the earth’s crust
Essential mineral
Bluish white metal
Less dense than iron and has a crystal structure
Hard and britte but becomes malleable between 100 to 150 degrees celcius
0.0075% of elements in earth’s crust

Examples of ElEMENTS (NON METALS):

Argon
Symbol: Ar
Physical state: gas
Atomic number:18
Group:18
3rd most common gas in earth’s atmosphere
Approximately the same solubility in water as oxygen
Coulourless, odourless

Bromine
Symbol: Br
Physical state: liquid
Atomic number: 35
Group: 17
Only non metallic element that is a liquid at room temperature
Melting point: -7.2 degrees Celsius
A dense, slightly transparent liquid
Evaporates easily at a specific temperature
Reacts vigorously with metals

Carbon
Symbol: C
Physical state: Solid
Atomic number: 6
18.5% of all elements in human body
Uses: pencil leads, fuel, constitutes living tissues
Group: 14
Highest melting and sublimation point of all elements
Period: 2
15th most abundant element in earth’s crust
3th most abundant element in the universe by mass

Chlorine
Symbol: Cl
Physical state: gas
Atomic number: 17
Used in bleaches for our clothes
Group: 17
Pure chlorine supports combustion of oranic compounds
Melting point: -150.7 F
Boiling point: -29.27 F

What is a compound???

"A compound is a substance containing two or more elements chemically joined together".

Fact #1 about compounds: Properties of compounds are different from the properties of their constituent elements
Fact #2: Compounds are made up of molecules and ions

Example of compounds: 1) Water
2) Calcium carbonate
3) Sucrose

Mixtures:

"Consists of two or more substances that are not chemically joined together"
Fact #1: It can consist of elements, compounds or both
Fact #2: Substances in a mixture can be solid, liquid or gas
Examples of mixutres: Brass, Seawater, Air

Last but not least, VIDEOS! ENJOY>>>

http://www.youtube.com/watch?v=GFIvXVMbII0 (Copy & Paste this url)
http://www.youtube.com/watch?v=A5H6DVe5FAI (Copy & Paste this url)

Acknowledgments:
1) School textbooks
2) Wikipedia
3) Ehow
4) Google images
5) Chemistry books from library
6) YOUTUBE

Written by: Ethan Teo