unit 2 lecture s2015

Intro moments

• Various students will research & share– Date & key idea or finding

1.J.J. Thomson

2.Rutherford

3.Dalton

4.Proton, neutron, & electron (how discovered)5.P+, No, e- (how can you use the periodic table to determine these values)

WEBSITES

• www.tinyurl.com/mrkicker– For assignments and downloading documents you may want

to print

• https://classroom.google.com– For vocab and online forms (won’t need to make copies)

turn in online with button

• http://learn.kearneypublicschools.org/– For blogs, practice tests, quizlets, etc.

• http://www.classzone.com/– Our online book

Book Problems to do• Chapter 3 book questions Chemistry (not

section 3.4) sample problems Read pg 49-67 & 76-83

– Read pg 49-67 & 76-83

– Pg 59 2, 4, 5, 6

– Pg 67 # 1, 2, 3, 4, 5, 7

– Pg 83 1, 2, 5

– Pg 86-88 # 12, 16, 17, 19, 20, 22, 23, 24, 28, 29, 30, 45 (use # with letter) 46

Periodic Table

• Look at the values on PT

• Larger # is mass

• Smaller (whole #) is atomic #

What determines an Element

•Proton!– This is a positive charged sub atomic particle

– The atomic number equals the # of P+s

Strong force

• Protons don’t like each other so what holds them together?

• Neutrons (these act like glue) – No charge, about the same mass & size

of P+

– Mass of an atom is P+s + Nos

Atoms are neutral

• There are electrons that surround the nucleus. The number of P+ equals # of e-s

Let’s try a couple …

• WS (all but last two)

• Ions are charged atoms. These are different from atoms. Same P+ & No, but different number of e-s

What does Kicker Mean?

• What determines the atom?– What does this mean:

• What particle does the chemistry?– Where are these particles located?

Determine the subatomic particles

• See page 65

• Determine subatomic particles for

• Ti

Make this symbolism for an atom / ion with 11 p+ 12 No and 11 e-

Make this symbolism for atom / ion with 52 p+ 75 No and 54 e-

What is a model? –It is an idea or representation of something

–It must act like what we are talking about and is used to predict things!

Atomic theory

Dalton (sphere)

Thomson (electron)

Rutherford (dense positive nucleus & huge empty space)

Later we find the size of subatomic particles & charges of them….

John Dalton (1766-1844)

• The idea of atoms had been proposed much earlier. The ancient Greek philosophers had talked about atoms, but Dalton's theory was different in that it had the weight of careful chemical measurements behind it.

DALTON’S ATOMIC THEORY

1. All elements are composed of tiny indivisible particles called atoms.

2. Atoms of the same element are identical. Atoms of any one element are different from those of another element. (hydrogen and helium, oxygen and nitrogen)

3. Atoms of different elements can physically mix together or can chemically combine with one another in simple whole number ratios to form compounds

4. Chemical reactions occur when atoms are separated, joined, or rearranged. Atoms of one element however are never changed into atoms of another element as a result of a chemical reaction.

DALTON’S ATOMIC THEORY

1.All elements are composed of tiny particles called atoms.

DALTON’S ATOMIC THEORY

2 Atoms of the same element are identical.

DALTON’S ATOMIC THEORY

3. Atoms of any one element are different from those of another element. (ex. hydrogen, oxygen

and nitrogen)

DALTON’S ATOMIC THEORY

4. atoms of different elements can physically mix together or can chemically combine with one another in simple whole number ratios to form compounds

DALTON’S ATOMIC THEORY

5. Atoms are indivisible in a chemical process. They can not be created nor destroyed. Atoms of one element are never changed into atoms of another element as a result of a chemical reaction. They are grouped together differently.

John Dalton (early 1800’s)• Said elements combined in the same

percentage by mass. In other words: Atoms of different elements always combine in fixed number ratios to produce specific compounds.

• We know this as law of definite proportions (or constant composition)

• Dalton’s Model - indivisible sphere with uniform density throughout.

Sir William Crookes - 1870’s• Put electrodes in a glass tube.

• Got a green “beam”• Tested with magnet and the beam bent - it

contained PARTICLES!

• Further experimentation deduced that the beam was negative in charge.

• Developed the cathode ray tube - ex...

Crookes tube video clip

Thomson’s model and the cathode

ray tube

• Thomson’s experiments provided the first evidence that atoms are made of even smaller particles.

J.J. Thomson - 1897• Set up CRT. Using magnets and charged

electric plates, was able to determine:– - the particles in the CRT always had the

same ratio of charge and mass regardless of the gas used.

– The gas bent the same, regardless of element

– - the particles were identical to each other– Particles were subatomic and found in all

atoms.

J.J. Thomson - continued

• Thomson credited with discovering the first type of subatomic particle - the electron

• Electron - negatively charged particle found in atoms.

J.J. Thomson - some more

• Discovered a second beam, going the opposite direction of the previous beam

• Charge equal, but opposite to the electron.

• He revised Dalton’s model to his own and called it the Plum Pudding model.

Summary

• Thomson’s second particle was a proton.

• Equal but opposite in charge to an electron

• 1836 times more massive than an electron

Rutherford

• Found evidence that the atom has a small core, a nucleus. Suggested that the atom might resemble a tiny solar system, with a massive, positively charged center circled by only a few electrons.

Ernest Rutherford - 1909

• Used alpha particles (from radioactive decay) to bombard targets made of sheets of gold.

• Positive alpha particles, according to Thomson’s model should have been repelled evenly and go straight through.

• However, some were deflected.

Ernest Rutherford - continued

• Thomson’s Model didn’t explain deflections

• Rutherford theorized that the atom had a small dense nucleus with 99.9 % of the mass, and the electrons hovered around that nucleus in mostly an empty space or cloud

READ THE CHAPTER

• Test– On moodle: code 1

• Reading start book probs & vocabulary

• We’ll start here tomorrow– Bring a key or something to plate (coin)

GRADES & TEST

• Blogs due ASAP

• STOP IN IF YOU DON’T GET IT

• READ THE CHAPTER

• OUTLINE NOTES AFTER THE POWERPOINT ( fill in the key ideas of the unit here)

• I.  Dalton and the beginning of the Atomic Theory

• II.  Thomsen’s Cathode Ray Tube Experiment

• III.  The subatomic particles in the atom. * values on the periodic table tell us a lot WS

• IV.  Rutherford’s Gold Foil Experiment * LAB

• V.  Atoms and their ions.  Cations and Anions * We DO WS

• VI.  Isotopes, mass number, atomic number and charge.

What do we know now?• Protons + • Neutrons 0• Electrons -

• The atom is mostly empty space with electrons taking up most of the volume and nucleus has most of the mass.

Same size found in nucleus

Very tiny (1/2000) size of hydrogen.

ISOTOPES

• Are atoms of the same element that have different numbers of neutrons. See pg 64

GO THRU PACKET PAGES

Try Rutherford lab

======

A meter stick for a backstop

Randomly placed marbles in setup.

Ions

• Ions are charged atoms.

• If the proton determines the atom, what would have to move in order for an atom to become charged?

• How many p+, No & e-

• Li Li+1

• O O-2

See patterns on PT

• Tomorrow Cu Key Lab & packet work.– pg 7-9 due tomorrow & PDPS– Pg 10-11 due on Thurs along with book probs– Online Vocabulary

– Everyone: check your grades!

Book Problems to do• Chapter 3 book questions Chemistry (not

section 3.4) sample problems Read pg 49-67 & 76-83

– Read pg 49-67 & 76-83

– Pg 59 2, 4, 5, 6

– Pg 67 # 1, 2, 3, 4, 5, 7

– Pg 83 1, 2, 5

– Pg 86-88 # 12, 16, 17, 19, 20, 22, 23, 24, 28, 29, 30, 45 (use # with letter) 46

Copper Plating experiment

ASSIGNMENT In Class

• Do Copper Key Lab Now– Read handout & discuss what plating is– Lab – In groups do worksheets in packet and discuss

book probs.

• PDPs - TIME TO MAKE SOME

Last day

• Ions & charges

• Putting some elements together– Simple binary

• Book probs: pg 86-89 , 45, 46, 52

• CH REVIEW SUMMARY WS packet pg 20-21