Chapter 4, Atomic TheoryWOD are underlined

Each block is an element.

Learn the name and symbol for elements 1-20 (quiz on Friday)

Read off the names of the 20 and symbols.

Dalton’s atomic theory

4 parts to describing an Atom. Dalton was not correct but “Close Enough to Count!”

Dalton’s atomic theory

1. Elements are composed of

submicroscopic atoms and are

indivisible.Smallest part of an element is an

atom.  

Can we divide an atom?What happens if you do?

If you divide an atom smaller than an atom, it stops acting like

the element and loses it’s elemental properties.

So Dalton was,“Close enough to count”.

Dalton’s atomic theory (Not correct, should be same isotope)

2. Atoms of the same element are identical

Should be:Atoms of the same element have the same chemical properties and

are therefore almost identical.OR

Atoms of the same isotope are identical.

So he was,“Close enough to count”.

3. Atoms can combine with one another in simple whole-number ratios

to form compounds(Means water is always 2 H and 1 O.)

  Compound means “Fixed Ratio” like H20, not like salt water, a mixture of NaCl and H20.

 4. Chemical reactions occur when

atoms are separated, joined, or rearranged. Atoms are never

changed into a different element.

Who was the king of alchemy? Midas and his golden touch.

building blocks of atoms: electrons, protons, neutrons

WOD’s at end of this section.

Protons positive chargein nucleus, p+

mass 1.0 AMU

Define 1.0 AMU as the mass of 1 proton

Neutrons in nucleus, no

1.0AMU no charge

Electrons (e-) are the smallest negative charge

mass 0.0005 AMU (count as 0 AMU)2000 e- = size of 1 p+

Electrons (e-) are the smallest negative charge Thank you for TV!!!!

Purple = magnetic charge

Screen is RGB dots.1 dot is a pixel.

Protons and Neutrons are found in the tiny nucleus.

Electrons surround the nucleus in a vast cloud. The electron cloud is

many times bigger than the nucleus.

If the nucleus were the size of a marble, then

the electron cloud would be

the size of What? Guess.

If the nucleus were the size of a marble and placed on the middle of the 50 yard line, then the atom or

electron cloud would be the size of Chief’s Arrowhead Stadium

Break up a 2nd marble into 2000 pieces. For Carbon 12, pick 6 of those pieces and scatter around

Arrowhead. Those 6 are the e- cloud.

Nucleus = marble and on the middle of the 50 yard line.

Electron cloud = size of Chief’s Arrowhead Stadium.

Then WHAT IS MOST of an Atom made up of????

So what is our brains made out of?

Is the wall behind me solid or is it empty space???

In an atom, what is

BIG Protons and

NeutronsSMALL Electrons

(and everything else???)

WOD Definitions:Atom’s Parts: Proton, Neutron, ElectronAtomic Mass Unit: AMU, Mass of 1 proton and standard mass measurement.Proton: positive charge, in nucleus, p+,mass 1.0 AMU Neutron: neutral charge, in nucleus, no,mass 1.0 AMU (think as size = p+) Close enough to count!

Electron: negative charge, orbitals (orbit), e- , very small so count as 0 AMU.Nucleus: Center of an atom = p+ and no.

Memorize Name and Symbol

Atomic number = protonsWhole number. It is number of protons in the nucleus of that

element

He = Atomic number of 2

How many protons does Ne ALWAYS have?

Look in inside back of textbook.

Atomic mass = proton + neutrons.total number of protons and neutrons

in the nucleus

He = Atomic mass of 4

Carbon 14Name followed by atomic mass.

C 14: Name is Carbon which means 6 protons and 6 electrons.

14 means protons + neutrons = 14, i.e., 8 neutrons.

What is different about Carbon 12?

Carbon 12Name followed by atomic mass.

C 12: Name is Carbon which means 6 protons and 6 electrons.

12 means protons + neutrons = 12, i.e., 6 neutrons.

It has 2 less neutrons than Carbon 14?

HW:Fill out the next page.

 

ElementName/

Symbol

Protons Mass number

Electron Atomic Number

Average Neutron

CarbonC

Be

Ne

15.999

7

Day 2

Day 2: Atomic structure

 

ElementName/

Symbol

ProtonsWRITENOTES HERE

Mass numberWRITENOTES HERE

ElectronWRITENOTES HERE

Atomic NumberWRITENOTES HERE

Average NeutronWRITENOTES HERE

CarbonC

See next page for

notes.

Be

Ne

15.999

7

“Write Notes Here” from previous page.

Write the following in the correct places on your HW. Use some twice.

p+, e-, no, = At#= p+ + no

= p+ (two places)= Mass - At#Pos, Neutral, Neg.

Big SmallNucleusOrbits1 AMU0 AMU

Isotopes – different numbers of neutrons. Same number of

protons, same element. # of Protons or Atomic Number

determines the chemical behavior of an element. So Isotopes of the

same element behave the same way Chemically. Very hard to

separate isotopes.

1 or 2 Pencils in hand of a sprinter.

Isotopes – different numbers of neutrons. Same number of

protons, same element, Carbon 12, Carbon 13, Carbon 14

What is H3 or C14 known for?

Average atomic mass – average mass of all isotopes found in

nature of an element (shown on P-table)

calculating average atomic mass-number of stable isotopes of that element

-mass of each isotope-natural percent abundance of each isotope

Formula (mass × decimal abundance) then add togetherDon’t worry if you don’t follow, we will show several examples.

Fictional element X

The above two isotopes are found. What is the average atomic mass of this fictional element X?

The above two isotopes are found. What is the average atomic mass of this fictional element X? 14amu (.7200) + 15amu (.2800)=14.28 amu

14.28 would be the number on the periodic table

14.28 would be the number on the periodic table NOTES: 1.) 14.28 does not end in .000, so it must have isotopes.2.) 14.28 is closest to 14, so 14 is the most common isotope in nature.3.) .28 is bigger than .000, so the other isotopes are most often 1 bigger than 14. (Approximation, not a law)

A chemical is found to have three isotopes, what is the average atomic mass of this element?

54amu 72.00% 55amu 25.00%57amu 3.000%

A chemical is found to have three isotopes, what is the average atomic mass of this element?

54amu 72.00% 55amu 25.00%57amu 3.000%

54 amu x .7200 + 55amu x .2500 + 57amu x .03000 =38.88amu + 13.75 amu + 1.71amu = 54.34 amu

On average how many protons does carbon have?

On average how many neutrons does Cl have?

Elements and chemical symbolsH=Hydrogen

You need to know 1-20 for the test

Another Periodic Table example:Different Periodic tables arrange the info in a different order.

Memorize Name and Symbol

Atomic number = the number of protons in the nucleus

Average Atomic mass = the number of protons plus the

average number of neutrons in the nucleus

                 

Ernest Rutherford won1908 Nobel Prize forstudies in radioactivity;discovered nucleus in 1911.

Ernest Rutherford was

the first to show thatthe atom does nothave uniform density,and that most of the itsmass is located at itscenter.

 

Ernest Rutherford-gold foil test proposed dense positively charged nucleus

The Nucleus 

                                                                           

Show demo with laser light on wall and Bohr atom model.Hold Bohr model in front of projector and draw light on boardShowing outline of nucleus.Describe Weds lab with marbles under a cardboard box.

Next ChapterThe Bohr Model of the Atom One of the simplest working

models of the atom is that developed by Niels Bohr. In this,

a central nucleus containing protons and neutrons is orbited by electrons. The electrons are arranged in shells or energy

levels.

Extra Material if time permits

Element song

Periodic table- elements arranged according to similarities in their

physical and chemical properties

periods – horizontal rows of the periodic table, properties change as you go across period, similar

for each period

groups – vertical columns on the p-table, similar

properties