Atom

And Atomic structure

Atom: Every substance is made up of atom

Atomic theory• Democritus(400BC):

All Substances of tiny indivisible particles called atom.

• John Dalton(1808):

1. All matter consisted of small indivisible particle.

2. Atom of same element are alike

3. Atoms are combined in simple whole number ratios.

J.J Thomson(1897):

Atom is a sphere of positive matter in which electrons are positioned by electrostatic forces.

Major portion of the atom is empty.

Rutherford

The whole mass of the atom is concentrated in the centre of atom called nucleus. The positively charged particles are present in the nucleus of atom. The electrons revolve

around the nucleus in different circular orbits. Size of nucleus is very small as compare to the size of atom.

Short video on atom

http://www.bbc.co.uk/schools/gcsebitesize/science/aqa/fundamentals/

Introduction to the Periodic Table

Atomic Number ● Symbol ● Atomic Weight

Element ● Compound ● Mixture

Dmitri menDeleev

Creation of PERIODIC TABLE !

PERIODIC TABLE

Shows all known elements in the universe.

Organizes the elements by chemical properties.

How do you read the PERIODIC TABLE?

What is the ATOMIC NUMBER?

o The number of protons found in the nucleus of an atom

Oro The number of electrons surrounding the nucleus of an atom.

What is the SYMBOL?

o An abbreviation of the element name.

What is the ATOMIC WEIGHT?

o The number of protons and neutrons in the nucleus of an atom.

How do I find the number of protons, electrons, and neutrons in an element using the periodic table?

o # of PROTONS = ATOMIC NUMBER

o # of ELECTRONS = ATOMIC NUMBER

o # of NEUTRONS = ATOMIC _ ATOMIC

WEIGHT NUMBER

Video on periodic table

http://www.bbc.co.uk/schools/gcsebitesize/science/aqa/fundamentals/theperiodictableact.shtml

Google web side to learn more about periodic table

www.chemicalelements.com/

Home Work

Go to web side and make brief notes of page 1 and 2. Draw atomic structure and clearly mention number of electron, proton, and neutron.

What is an ELEMENT?

o A substance composed of a single kind of atom.

o Cannot be broken down into another substance by chemical or physical means.

What is a COMPOUND?

o A substance in which two or more different elements are CHEMICALLY bonded together.

What is a MIXTURE?

o Two or more substances that are mixed together but are NOT chemically bonded.

Element, Compound or Mixture?

Element, Compound or Mixture?

Element, Compound or Mixture?

Element, Compound or Mixture?

Element, Compound or Mixture?