Term 3-elements,compound and mixture

Elements

An element is a substance which cannot be broken down into two or more simpler substances by chemical methods.

Elements are the simplest kind of matter.

There are more than 100 elements in the universe.

All discovered elements are listed in the Periodic Table.

The Periodic Table

As you can see,elements are represented by a unique symbol,usually consisting of one or two letters,some are easy to remember as they are the initial of english words but other words are Latin,so it depends on each individual.

Classifying elements

The periodic table is a very organised system.

Elements have been placed systematically into the Periodic Table according to their properties.

Scientists have classified elements into 2 main groups, the metals and non-metals.

Each vertical column is called a period. Each group’s number is reflected at the top of the periodic table.

Elements in the same group have similar properties and will undergo the same type of chemical reactions. Each group has its own unique properties.

Each horizontal row is called a group.

The periods are numbered from the top row down.

Elements in a period from left to right show a gradual change from metallic to non-metallic_.

Elements to the left of the zig-zag line in the Periodic Table are metals, while those to the right of the zig-zag line are non-metals.

Compounds

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

The properties of the compound formed have different properties from the constituent elements

Compounds cannot be broken down by physical methods,it 
can ONLY be broken down by chemical methods.

It is in fixed proportion by ratio.

Mixture

It is the only impure substance out of the three classification,elements and compounds are pure while only mixture are impure...

A mixture consists of two of more different substances that are mixed but not chemically joined together.

Simplest examples:

—  a mixture of 2 elements
—a mixture of 2 compounds
—a mixture of an element and a compound

¢Air

—mixture of gases

—contains N2 , O2 , Ar, CO2 , H2O (gas), methane and other inert gases.

—

¢ Seawater

—exist as liquid

—contains water and sodium chloride

—

¢Brass

—exist as solid

—mixture of copper and zinc

A mixture has variable composition. It can only be separated by physical means like distillation and filtration.

Solutions are also mixtures.Now,I will be talking about them......

•All solutions consist of 2 parts

–Solvent (the substance that does the dissolving, makes up the majority of the solution – usually liquid, but can also be solid or gas)

–Solute (the substance that dissolves – can be solid, liquid or gas)

Examples

Iodine is a non-metallic element that sublimes when heated to form a violet vapour.

When dissolved in ethanol, it forms tincture of iodine, used as an antiseptic.

Solubility 

•The solubility of a substance in a solvent is the maximum quantity of that substance which can dissolve in 100 g of the solvent at a given temperature

•(units: g / 100 g)

Types of solution

•Copper(II) sulfate has a solubility of 32 g /100 g in water (at 20°C)

•Copper(II) sulfate has a solubility of 32 g /100 g of solvent (at 20°C)

•100 g of water (100 ml)

–2 g of copper(II) sulfate-dilute solution

–30 g of copper(II) sulfate-concentrated solution

–32 g of copper(II) sulfate-saturated solution

–35 g of copper(II) sulfate-suspension 

Factors affecting solubility

•Type of solute

type of solvent 

•Temperature of solvent

•Pressure of surroundings

Suspension

When the amount of substance present is over its solubility limit,

the substance does not dissolve in the solvent

•Factors affecting rate of dissolving

–Temperature of solvent

–Particle size of solute

Stirring

Source: Powerpoints in Ivle

Reflection

I feel that one has to fluent in understanding these properties to relate them to real life applications like the swirling of lemon tea in the canteen before taking a sip,the making of alloys like brass instruments in companies and the chemical reactions that takes place when rockets,Apollo, is able to launch.In conclusion,besides studying the properties of the classification and absorbing them,i should study the link to situations when we have indigestion,a city having more solubility of air than a village and so more.....into my aces......:DDDD