atoms - matter is made up of elements and elements in turn are made up of atoms. - macroscopic world...

21
ATOMS - Matter is made up of elements and elements in turn are made up of atoms. - Macroscopic world v. Microscopic world - The unraveling of the structure of the atom is like working on a jigsaw puzzle,

Upload: marilyn-thompson

Post on 13-Dec-2015

221 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: ATOMS - Matter is made up of elements and elements in turn are made up of atoms. - Macroscopic world v. Microscopic world - The unraveling of the structure

ATOMS

- Matter is made up of elements and elements in

turn are made up of atoms.

- Macroscopic world v. Microscopic world

- The unraveling of the structure of the atom is like

working on a jigsaw puzzle, only this puzzle took

almost 50 years to complete and not just by one

scientist alone.

Page 2: ATOMS - Matter is made up of elements and elements in turn are made up of atoms. - Macroscopic world v. Microscopic world - The unraveling of the structure

ATOM

Take a piece of chalk. from a Greek word “atomos” which

means indivisible The smallest unit of an element that

still has the properties of that element 1-inch line of gold = 88 million atoms

Page 3: ATOMS - Matter is made up of elements and elements in turn are made up of atoms. - Macroscopic world v. Microscopic world - The unraveling of the structure

MOLECULE

Is a unit of a substance that can exist freely and posses all the properties of a given substance

a neutral chemically bonded group of atoms that acts as a unit

There are molecules that consist of only one atom, not group of them.

Page 4: ATOMS - Matter is made up of elements and elements in turn are made up of atoms. - Macroscopic world v. Microscopic world - The unraveling of the structure

MOLECULES

Examples1. He = O O O O = 4units/molecules

each has 1 atom2. O2 = = 2 molecules each

contains 2 atoms 3. P = = 2 molecules each

has 4 atoms

Page 5: ATOMS - Matter is made up of elements and elements in turn are made up of atoms. - Macroscopic world v. Microscopic world - The unraveling of the structure

What is the true picture of an atom?

Today, the field ion microscope (by

Erwin Mueller, 1956) and the Scanning

Tunneling microscope (STM) (by the

IBM scientists, 1980’s), give us clear

images of the atom

Page 6: ATOMS - Matter is made up of elements and elements in turn are made up of atoms. - Macroscopic world v. Microscopic world - The unraveling of the structure

DEVELOPMENT OF THE ATOMIC STRUCTURE

I. Early Ideas about the Atom

- (460 – 370 B.C.) Democritus of Abdera, Greece, a

famous teacher of “Atomists school of thought

suggested the idea of the atoms using a piece of gold

- Claimed that atoms are invisible, indestructible

fundamental or smallest particles of matter

- His theory was ignored because he lacked

experimental proof to back it up.

Page 7: ATOMS - Matter is made up of elements and elements in turn are made up of atoms. - Macroscopic world v. Microscopic world - The unraveling of the structure

DEVELOPMENT OF THE ATOMIC STRUCTURE

Plato and Aristotle - Both were prominent philosophers,

demanded that atoms be shown to them.

- Rejected the atomism claiming that this idea challenged the existence of God.

- Said that you can divide anything endlessly.

Page 8: ATOMS - Matter is made up of elements and elements in turn are made up of atoms. - Macroscopic world v. Microscopic world - The unraveling of the structure

DEVELOPMENT OF THE ATOMIC STRUCTURE

Later, atomic idea was picked up by

other scientists like Galileo, Francis

Bacon, Robert Boyle, and Isaac Newton

who used the atomic idea to understand

and explain visible events.

Page 9: ATOMS - Matter is made up of elements and elements in turn are made up of atoms. - Macroscopic world v. Microscopic world - The unraveling of the structure

DEMOCRITUS’ ATOMIC MODEL

Page 10: ATOMS - Matter is made up of elements and elements in turn are made up of atoms. - Macroscopic world v. Microscopic world - The unraveling of the structure

DEVELOPMENT OF THE ATOMIC STRUCTURE

II. DALTON’S ATOMIC THEORY

- (1766-1844) John Dalton, an English school teacher

at age 12 revived the idea of the atom after 2200

years.

- Major Assumptions of DAT (1805)

1. Matter consists of tiny, indestructible particles called

atoms. They remain unchanged during chemical

reactions.

Page 11: ATOMS - Matter is made up of elements and elements in turn are made up of atoms. - Macroscopic world v. Microscopic world - The unraveling of the structure

DEVELOPMENT OF THE ATOMIC STRUCTURE

2. Atoms of a particular element all have the same properties (size, shape, mass) different from those of other elements.

3. Atoms combine in simple/small number ratios when they form compounds.

4. A chem’l change involves the joining, separation or rearrangement of atoms in the compounds.

Page 12: ATOMS - Matter is made up of elements and elements in turn are made up of atoms. - Macroscopic world v. Microscopic world - The unraveling of the structure

DEVELOPMENT OF THE ATOMIC STRUCTURE

Despite its flaws, this theory was accepted for it explained adequately 2 important laws of chemical combination.

1. The Law of Conservation of Mass2. The Law of Constant/Definite

Composition

Page 13: ATOMS - Matter is made up of elements and elements in turn are made up of atoms. - Macroscopic world v. Microscopic world - The unraveling of the structure

DEVELOPMENT OF THE ATOMIC STRUCTURE

The Law of Conservation of Mass- States that no new atoms are gained or

lost during a chem’l rxn, thus the mass during the rxn is unchanged. Atoms merely regrouped themselves.

- Wood + O2 = ashes + smoke+ vapor (total mass) = (total mass)

Page 14: ATOMS - Matter is made up of elements and elements in turn are made up of atoms. - Macroscopic world v. Microscopic world - The unraveling of the structure

DEVELOPMENT OF THE ATOMIC STRUCTURE

The Law of Constant/Definite Composition (Joseph Proust, 1794)

- States that a pure compound always consists of the same elements combined in the same mass ratio.

- Ex. H2O = 2H + 1O (2:1) NaCl = 1Na + 1Cl (1:1)

Page 15: ATOMS - Matter is made up of elements and elements in turn are made up of atoms. - Macroscopic world v. Microscopic world - The unraveling of the structure

DALTON’S ATOMIC MODEL

Dalton strengthened

Democritus’ idea

Page 16: ATOMS - Matter is made up of elements and elements in turn are made up of atoms. - Macroscopic world v. Microscopic world - The unraveling of the structure

REVISIONS OF THE D.A.T.

1. Atoms are divisible, consist of subatomic particles.

2. Atoms of the same elements have different masses. Isotopes

3. Atoms are not permanent. They can be converted to another atoms or be destroyed after certain nuclear processes. Ex. Ra - Rn - Po

Page 17: ATOMS - Matter is made up of elements and elements in turn are made up of atoms. - Macroscopic world v. Microscopic world - The unraveling of the structure

ISOTOPES

are atoms of the same element but with different masses.

have the same number of protons/atomic no. but different number of neutrons/mass no.

Ex. H – protium, 0 neutron H - deuterium, 1 neutron H - tritium, 2 neutrons

Page 18: ATOMS - Matter is made up of elements and elements in turn are made up of atoms. - Macroscopic world v. Microscopic world - The unraveling of the structure

YOUR TURN

10 – ITEM QUIZ

Page 19: ATOMS - Matter is made up of elements and elements in turn are made up of atoms. - Macroscopic world v. Microscopic world - The unraveling of the structure

QUIZ

DIRECTIONS: Answer the ff. correctly.1. Draw Democritus’ atomic model.2. Draw Dalton’s atomic model.3. Name the 2 philosophers who rejected

Democritus’ atomic idea.4. Who is the father of atomic theory?5. Who is the father of the modern atomic

theory?

Page 20: ATOMS - Matter is made up of elements and elements in turn are made up of atoms. - Macroscopic world v. Microscopic world - The unraveling of the structure

QUIZ

6. This law states that mass is conserved during a chemical rxn.

7. Atom comes from a Greek word ___

8. Give an example of a one-atom molecule.

9. Give one microscope used to see atoms.

10. 1-inch line of gold has how many atoms?

Page 21: ATOMS - Matter is made up of elements and elements in turn are made up of atoms. - Macroscopic world v. Microscopic world - The unraveling of the structure

Tomorrow

Let’s talk about Thomson,

Rutherford, and Bohr