Chapter 17 - cp Atoms. 4.2/4.3 The Structure of the Atom & Modern Atomic Theory JOURNAL: 1. QUIETLY work on the Atomic Math worksheet FIRST 2. Then, work.

Chapter 17 - cpChapter 17 - cp

AtomsAtoms

4.2/4.3 The Structure of the Atom & Modern 4.2/4.3 The Structure of the Atom & Modern Atomic TheoryAtomic Theory

JOURNALJOURNAL: : 1.1. QUIETLY work on the Atomic Math QUIETLY work on the Atomic Math

worksheet FIRSTworksheet FIRST

2.2. Then, work on the“Not So Bohr-ing Then, work on the“Not So Bohr-ing Atoms” Worksheet from the back table. Atoms” Worksheet from the back table.

3.3. Use the Periodic Table I gave you to help Use the Periodic Table I gave you to help you.you.

Studying AtomsStudying Atoms

ANCIENT GREEKS-ANCIENT GREEKS-DEMOCRITUS:DEMOCRITUS:

““atomos” = indivisible, uncutatomos” = indivisible, uncut Different types of atoms with specific Different types of atoms with specific

propertiesproperties

ARISTOTLE:ARISTOTLE: Only 4 elements Only 4 elements No limit to divisionsNo limit to divisions

Studying AtomsStudying AtomsDALTON’S ATOMIC THEORY:DALTON’S ATOMIC THEORY: all matter is all matter is made of particles that cannot be dividedmade of particles that cannot be divided

Evidence:Evidence: Compounds have fixed compositionsCompounds have fixed compositions

HH22OO Chemical reactions are a rearrangement of Chemical reactions are a rearrangement of

solid atoms.solid atoms.

Studying AtomsStudying AtomsTHOMSON’S ATOMIC THEORY:THOMSON’S ATOMIC THEORY: all matter is all matter is made of particles that made of particles that CANCAN be divided be dividedEVIDENCEEVIDENCE::

Particles collected on metal plateParticles collected on metal plate The particles ALWAYS had a mass 1/2000 of a The particles ALWAYS had a mass 1/2000 of a

Hydrogen atom.Hydrogen atom. The beam was always attracted to the positive The beam was always attracted to the positive

sideside

Thomson’s “plum pudding” Atomic Thomson’s “plum pudding” Atomic ModelModel

Explained neutral atoms with charges

Studying AtomsStudying AtomsRUTHERFORD’S ATOMIC THEORY:RUTHERFORD’S ATOMIC THEORY: all atoms all atoms positive charge is concentrated in the positive charge is concentrated in the nucleusnucleus

Thomson’s “plum pudding” Thomson’s “plum pudding” Atomic ModelAtomic Model

Studying AtomsStudying AtomsRUTHERFORD’S ATOMIC THEORY:RUTHERFORD’S ATOMIC THEORY: all atoms all atoms positive charge is concentrated in the positive charge is concentrated in the nucleusnucleus

Discovered:Discovered: Uranium emits fast moving positive particlesUranium emits fast moving positive particles

Studying AtomsStudying AtomsRUTHERFORD’S ATOMIC THEORY:RUTHERFORD’S ATOMIC THEORY: all atoms all atoms positive charge is concentrated in the positive charge is concentrated in the nucleusnucleus

If you shoot these positive particles at other If you shoot these positive particles at other atoms (Thomson’s plum pudding atom), what atoms (Thomson’s plum pudding atom), what would happen to the particle?would happen to the particle?

SHOULD GO STRAIGHT THROUGH!!SHOULD GO STRAIGHT THROUGH!!

Studying Atoms – Gold Foil Studying Atoms – Gold Foil ExperimentExperiment

4.1 The Gold Foil Experiment4.1 The Gold Foil Experiment

RUTHERFORD’S ATOMIC THEORY:RUTHERFORD’S ATOMIC THEORY: all atoms positive charge is concentrated in the nucleusall atoms positive charge is concentrated in the nucleus

Studying Atoms – Modern Atomic Studying Atoms – Modern Atomic TheoryTheory

Bohr Atom:Bohr Atom: Electrons are in energy levelsElectrons are in energy levelsElectrons move when they gain or lose Electrons move when they gain or lose energy energy (example)(example)

Parts of an ATOM:Parts of an ATOM:

Subatomic particlesSubatomic particles – – distinguished by mass, charge distinguished by mass, charge

and locationand location

Subatomic particle PROPERTIESSubatomic particle PROPERTIES Protons (p+):Protons (p+):

In the nucleusIn the nucleus Charge of 1+Charge of 1+ Mass of 1Mass of 1 DEFINES THE ELEMENT DEFINES THE ELEMENT

(equals the ATOMIC NUMBER)(equals the ATOMIC NUMBER)

Protons (p+):Protons (p+): Atoms of DIFFERENT elements Atoms of DIFFERENT elements

have DIFFERENT numbers of have DIFFERENT numbers of protonsprotons

Subatomic particle PROPERTIESSubatomic particle PROPERTIES Neutrons (n°):Neutrons (n°):

In the nucleusIn the nucleus NO chargeNO charge Mass of 1Mass of 1 Protons + neutrons = Protons + neutrons = the ATOMIC the ATOMIC

MASSMASS

Neutrons (n°):Neutrons (n°): Atoms of the same element with Atoms of the same element with

DIFFERENT numbers of neutrons DIFFERENT numbers of neutrons are called are called

ISOTOPESISOTOPES

Neutrons (n°):Neutrons (n°): ISOTOPES of Hydrogen. ISOTOPES of Hydrogen. Same Same

Atomic #, different Mass #Atomic #, different Mass #

Electrons (e-):Electrons (e-): In ENERGY LEVELS around the nucleusIn ENERGY LEVELS around the nucleus Charge of 1-Charge of 1- Mass of 1/1836 of a p+Mass of 1/1836 of a p+ Equal to the number of protonsEqual to the number of protons The outermost shell of electrons is called The outermost shell of electrons is called

the VALENCE SHELL which holds the the VALENCE SHELL which holds the VALENCE ELECTRONS.VALENCE ELECTRONS.

Take out Bohr Diagram Sheet.

Electrons (e-):Electrons (e-): Change ENERGY LEVELS when the atom Change ENERGY LEVELS when the atom

GAINS or LOSES energyGAINS or LOSES energy

The most stable electron

arrangement

Electrons (e-):Electrons (e-): CurrentTheory – CurrentTheory – “Electron Cloud Model” (p116-17)“Electron Cloud Model” (p116-17)

Orbitals that show most PROBABLE location of electronsOrbitals that show most PROBABLE location of electrons

Electrons (e-):Electrons (e-): Atoms of the same element with different Atoms of the same element with different

number of ELECTRONS are called number of ELECTRONS are called IONSIONS

IONS:IONS: form to make the outermost shell stableform to make the outermost shell stable

4.2/4.3 The Structure of the Atom & Modern 4.2/4.3 The Structure of the Atom & Modern Atomic TheoryAtomic Theory

OCTET RULE:OCTET RULE:Take out a lined sheet of paper, draw a circle for a Take out a lined sheet of paper, draw a circle for a

nucleus and then three rings around the nucleus and then three rings around the nucleus.nucleus.

Protons and neutrons in nucleus

2 electrons in 1st shell

8 electrons in 2nd shell

8 electrons in 3rd shell

Atomic Number PracticeAtomic Number Practice

Use your periodic table to find the Use your periodic table to find the atomicatomic numbernumber of the of the following elements:following elements:

Aluminum (Al)Aluminum (Al) Titanium (Ti)Titanium (Ti) Tin (Sn)Tin (Sn) Osmium (Os)Osmium (Os) Erbium (Er)Erbium (Er)

How many protons does each atom have?How many protons does each atom have? The number of protons are equal to the atomic number.The number of protons are equal to the atomic number.

Al = 13Ti = 22Sn = 50Os = 76

Er = 68

Mass NumberMass Number

The The mass numbermass number of an atom is the sum of the of an atom is the sum of the number of protons and neutrons in the nucleus.number of protons and neutrons in the nucleus.

ElementElement ProtonsProtons NeutronsNeutrons Mass NumberMass Number

BoronBoron 55 66 5+65+6

CarbonCarbon 66 66 6+66+6

OxygenOxygen 88 88 8+88+8

SodiumSodium 1111 1212 11+1211+12

CopperCopper 2929 3434 29+3429+34

11

12

16

23

63

PracticePractice

Determine the number of protons and neutrons in Determine the number of protons and neutrons in the following atoms:the following atoms:

Lithium – Lithium – Atomic Number = 3Atomic Number = 3

Mass Number = 7Mass Number = 7Argon –Argon – Atomic Number = 18Atomic Number = 18

Mass Number = 39Mass Number = 39Strontium – Strontium – Atomic Number = 38Atomic Number = 38

Mass Number = 88Mass Number = 88

Atomic Number & Mass NumberAtomic Number & Mass Number

If you know the atomic number and mass If you know the atomic number and mass number, you can determine the number of number, you can determine the number of neutrons.neutrons.

Mass NumberMass Number

- Atomic Number- Atomic Number

Number of NeutronsNumber of Neutrons

AnswersAnswers

Determine the number of protons and neutrons in Determine the number of protons and neutrons in the following atoms:the following atoms:

Lithium – Lithium – Protons = 3Protons = 3

Neutrons = 7 – 3 = 4Neutrons = 7 – 3 = 4Argon –Argon – Protons = 18Protons = 18

Neutrons = 39 – 18 = 21Neutrons = 39 – 18 = 21Strontium – Strontium – Protons = 38Protons = 38

Neutrons = 88 – 38 = 50Neutrons = 88 – 38 = 50

Neutral AtomsNeutral Atoms

In the nucleus, which particles have In the nucleus, which particles have charge?charge?ProtonsProtons

What charge do they have?What charge do they have?PositivePositive

What particle is opposite that charge?What particle is opposite that charge?ElectronsElectrons

Neutral AtomsNeutral Atoms

In the atom:In the atom:

The number of protons equals the number of electrons.The number of protons equals the number of electrons.

Li has 3 protons, so has a charge of +3.Li has 3 protons, so has a charge of +3.Li also has 3 electrons that add up to -3.Li also has 3 electrons that add up to -3.ADDED TOGTHER, the overall charge is:ADDED TOGTHER, the overall charge is:

(+3) + (-3) = 0, so the atom is neutral.(+3) + (-3) = 0, so the atom is neutral.

PracticePractice

Determine how many electrons the following atoms have:Determine how many electrons the following atoms have:

Magnesium, Protons = 12Magnesium, Protons = 12Beryllium, Protons = 4Beryllium, Protons = 4Nitrogen, Atomic Number = 7Nitrogen, Atomic Number = 7Bromine, Atomic Number = 35Bromine, Atomic Number = 35

12 Electrons

4 Electrons7 Electrons

35 Electrons

Bohr Models of the AtomsBohr Models of the Atoms

Each atom has shells in which the electrons can Each atom has shells in which the electrons can fit.fit.

11stst Shell: fills to 2 electrons Shell: fills to 2 electrons22ndnd Shell: fills to 8 electrons Shell: fills to 8 electrons33rdrd Shell: fills to 18 electrons Shell: fills to 18 electrons44thth Shell: fills to 32 electrons Shell: fills to 32 electrons

Start filling the smallest/closest shell first.Start filling the smallest/closest shell first.

REVIEWREVIEW1.1. Draw a Bohr Atom Model of Hydrogen, Draw a Bohr Atom Model of Hydrogen,

Carbon, and Oxygen on the back of your Carbon, and Oxygen on the back of your worksheet.worksheet.

2.2. Which subatomic particles belong in the Which subatomic particles belong in the nucleus?nucleus?

3.3. Which subatomic particles belong on the Which subatomic particles belong on the rings?rings?

4.4. What is the difference between ‘ground What is the difference between ‘ground state’ and ‘excited state’ of an atom?state’ and ‘excited state’ of an atom?