Student Version Periodic Table powerpoint with basic atomic theory

Why are the masses on the periodic table decimal values if they reflect “whole” protons and neutrons?How are the masses determined?

Just when you thought it was only

Protons Neutrons And Electrons…

“HA HA HA! It never stops! Never! There’s always more!You will never know it all! MUAH HAH HAH HAH! Always more!”

- THE ATOMIC THEORY

Vertical columns are Families -

elements with similar properties.

Alkali Metals

Alkaline Earth Metals

Transition Metals

Rare Earth Metals

Boron Family

Carbon Family

Nitrogen Family

Oxygen Family

Halogen Family

Nobel Gas Family

• How do you study something that is invisible?“Ya throw stuff at it n’see how it bounces off, duh!”

-Sam “Bhatman” Bhat, atomic researcher, politician, toe nail enthusiast

• Complete the projectile activity by using a straightedge and common sense to determine the shape of the invisible object inside the box.– Some projectiles pass straight through in one side and out the

other (they hit nothing).– Some projectiles go in, hit something, and are reflected back

out (dbl sided arrow)– Some projectiles go in, hit something, and are deflected out at

an angle. Retrace the paths and see where they intersect.

http://mogk12.2ya.com/rutherford

http://library.thinkquest.org/19662/low/eng/index.html

Atom – The Incredible World (Thinkquest)

Record what you observed, what you changed/did, what you learned for each virtual lab!

Download the worksheets and complete the lab and questions. Turn it in when you are done.

Virtual Labs• Interactives: http://phet.colorado.edu/ • Click “play with sims” then “chemistry” then “Run

Now”– States of Matter– Balloons and static electricity– Rutherford Scattering– Build an Atom – Tutorial and Game– Isotopes and Atomic Mass– Atomic Interactions– Models of the Hydrogen Atom

Record what you observed, what you changed/did, what you learned for each virtual lab!

You will hand in your labs!

Virtual Labs• http://www.rsc.org/chemsoc/visualelements/page

s/pertable_fla.htm (Visual Elements Periodic Table)

Dalton’s Model

• In the early 1800s, the English Chemist John Dalton performed a number of experiments that eventually led to the acceptance of the idea of atoms.

Dalton’s Theory• He deduced that all elements

are composed of atoms. Atoms are indivisible and indestructible particles.

• Atoms of the same element are exactly alike.

• Atoms of different elements are different.

• Compounds are formed by the joining of atoms of two or more elements.

.

• This theory became one of the foundations of modern chemistry.

Thomson’s Plum Pudding Model

• In 1897, the English scientist J.J. Thomson provided the first hint that an atom is made of even smaller particles.

Thomson Model

• He proposed a model of the atom that is sometimes called the “Plum Pudding” model.

• Atoms were made from a positively charged substance with negatively charged electrons scattered about, like raisins in a pudding.

Thomson Model• Thomson studied

the passage of an electric current through a gas.

• As the current passed through the gas, it gave off rays of negatively charged particles.

Cathode Ray Tube

Thomson Model

• This surprised Thomson, because the atoms of the gas were uncharged. Where had the negative charges come from?

Where did they come from?

Thomson concluded that the negative charges came from within the atom.

A particle smaller than an atom had to exist.

The atom was divisible!

Thomson called the negatively charged “corpuscles,” today known as electrons.

Since the gas was known to be neutral, having no charge, he reasoned that there must be positively charged particles in the atom.

But he could never find them.

Cathode Rays

Had mass – albeit a very small amount; they pushed a lightweight paddlewheel up an incline.

They could do work!

Had direction – they passed from the negative to the positive electrode

Had charge they bent in an electric field (towards the positive plate) and in a magnetic field

Rutherford’s Gold Foil Experiment

• In 1908, the English physicist Ernest Rutherford was hard at work on an experiment that seemed to have little to do with unraveling the mysteries of the atomic structure.

• Rutherford’s experiment Involved firing a stream of tiny positively charged particles at a thin sheet of gold foil (2000 atoms thick)

• http://chemmovies.unl.edu/ChemAnime/RUTHERFD/RUTHERFD.html

http://chemmovies.unl.edu/ChemAnime/RUTHERFD/RUTHERFD.html

Alpha Particles = He nucleus2p+ + 2no

– Most of the positively charged “bullets” passed right through the gold atoms in the sheet of gold foil without changing course at all.

– Some of the positively charged “bullets,” however, did bounce away from the gold sheet as if they had hit something solid. He knew that positive charges repel positive charges.

You Try

• The radius of a hydrogen atom is 5 x 10-11

meters. The radius of a single proton is 5 x 10-

16 meters. Assuming that atoms take the most size – efficient shape, a sphere, determine how much of an atom is truly empty space free of matter.

• Vsphere = 4/3 π r3

Rutherford vs Thomson• This could only mean that the gold atoms in the

sheet were mostly open space. Atoms were not a pudding filled with a positively charged material.

• Rutherford concluded that an atom had a small, dense, positively charged center that repelled his positively charged “bullets.”

• He called the center of the atom the “nucleus”• The nucleus is tiny compared to the atom as a whole.

Crammin’ Spark

You will have a quiz on the correct placement of elements on the table from memory.

You Try

• The radius of a hydrogen atom is 5 x 10-11

meters. The radius of a single proton is 5 x 10-

16 meters. Assuming that atoms take the most size – efficient shape, a sphere, determine how much of an atom is truly empty space free of matter.

• Vsphere = 4/3 π r3

Rutherford• Rutherford reasoned that

all of an atom’s positively charged particles were contained in the nucleus.

• The negatively charged particles were scattered outside the nucleus around the atom’s edge.

Bohr Model• In 1913, the Danish

scientist Niels Bohr proposed an improvement. In his model, he placed each electron in a specific energy level.

Where did I put my electrons?

Bohr Model• According to Bohr’s

atomic model, electrons move in definite orbits around the nucleus, much like planets circle the sun. These orbits, or energy levels, are located at certain distances from the nucleus.

The Wave Model• Today’s atomic

model is based on the principles of wave mechanics.

• According to the theory of wave mechanics, electrons do not move about an atom in a definite path, like the planets around the sun.

Wave Model

Electrons are defined by 3-D regions of probability where electrons are found “most” often

But where are they when they’re not where we expect?

A final word about Mendeleev’s Table…

• Mendeleev’s combining powers or valences• Metals do not form compounds with other

metals• Metals and non-metals react as do non-

metals with non-metals • How?• Why?• Who cares?

It’s the electrons

• The nucleus does not change.• The number of electrons do change

– Atoms become “ions” and they are attracted to oppositely charged particles

– Ions are named according to Faraday and his study of electrolytes (salt water) and conduction

• The combining powers that Mendeleev found reflect the amount of negative charge lost or gained during a reaction

The oxidation number of an element indicates the number of electrons gained or lost when forming compounds.

Elements with positive oxidation numbers lose electrons. (cation)

Elements with negative oxidation numbers gain electrons. (anion)

+1

+2

+1, +2, +3

+3

+4 or -4

-3

-2

-1

Electron energy levels, from 1 to 7

Electron energy sublevels

Electron energy sublevel s

Electron energy sublevel p

Electron energy sublevel d

Electron energy sublevel f

Each "pair" of boxes in a sublevelindicates an orbital. Each orbital can hold up to 2 electrons…

How many electrons fit in the 3rd energy level? What about the 4th?Count the boxes to find your answer…

3

4

8

18

An Electron Configuration showsthe exact location of every electronin an atom.1s2 2s2 2p6 = Configuration for Neon

With very few exceptions, theelectron configuration of an atomcan be read directly from the Table.

S block

P block

D Block

F block

Electron Energy Levels Match Up with the Rows of the Periodic Table