Chapter 4 - HChapter 4 - H

AtomsAtoms

4.1 Journal – Using 4.1 Journal – Using AnalogiesAnalogiesThe network of blood vessels in your body is like the The network of blood vessels in your body is like the

network of streets and highways in a large city. network of streets and highways in a large city. How are the two networks similar? Both networks How are the two networks similar? Both networks are used to transport objects from one location to are used to transport objects from one location to another. The comparison is an example of an another. The comparison is an example of an analogy. An analogy uses a similarity to compare analogy. An analogy uses a similarity to compare two objects or systems. A familiar object is often two objects or systems. A familiar object is often used to help explain a less familiar object. used to help explain a less familiar object.

1.1. Atoms in compounds are like bricks in a wall. Atoms in compounds are like bricks in a wall. Explain Explain

this analogy. this analogy. 2.2. Think of and explain another analogy for atoms Think of and explain another analogy for atoms

in compounds.in compounds.3.3. WORK ON THE “ATOMIC MATH” WORKSHEET.WORK ON THE “ATOMIC MATH” WORKSHEET.

4.1 Studying Atoms4.1 Studying 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

4.1 Studying Atoms4.1 Studying 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

H2OH2O

2g H always combines with 8g O2g H always combines with 8g O

4g H always combines with 16g O4g H always combines with 16g O

4.1 Studying Atoms4.1 Studying 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 dividedMAIN POINTS:MAIN POINTS:

1) All matter is made of atoms. Atoms are indivisible and 1) All matter is made of atoms. Atoms are indivisible and indestructible.indestructible.

2) All atoms of a given element are identical in mass and 2) All atoms of a given element are identical in mass and propertiesproperties

3) Compounds are formed by a combination of two or 3) Compounds are formed by a combination of two or more different kinds of atoms.more different kinds of atoms.

H2O, CO2, CH4, H2SO4H2O, CO2, CH4, H2SO44) A chemical reaction is a 4) A chemical reaction is a rearrangementrearrangement of atoms. of atoms.

4.1 Studying Atoms4.1 Studying AtomsDALTON’S ATOMIC THEORY:DALTON’S ATOMIC THEORY:

4.1 Studying Atoms4.1 Studying AtomsTHOMSON’S ATOMIC THEORY:THOMSON’S ATOMIC THEORY: matter is matter is made of particles that made of particles that CANCAN be divided be divided

EVIDENCEEVIDENCE:: Conducted a current thru a tubeConducted a current thru a tube

4.1 Studying Atoms4.1 Studying 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::

No matter what metal was used, the particles No matter what metal was used, the particles had a mass 1/2000 of a Hydrogen atom.had a mass 1/2000 of a Hydrogen atom.

The beam was always attracted to the positive The beam was always attracted to the positive sideside

Hypothesis- these particles came from the Hypothesis- these particles came from the atoms.atoms.

4.1 Studying Atoms - Thomson’s 4.1 Studying Atoms - Thomson’s “plum pudding” Model“plum pudding” Model

The 'Plum Pudding' Model of an Atom

4.1 Studying Atoms4.1 Studying Atoms

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

4.1 Studying Atoms4.1 Studying AtomsRUTHERFORD’S ATOMIC THEORY:RUTHERFORD’S ATOMIC THEORY: all atoms all atoms positive charge is concentrated in the nucleuspositive charge is concentrated in the nucleus

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

HypothesisHypothesis:: If you shoot positive particles at gold foil (other If you shoot positive particles at gold foil (other

atoms), what would happen to the particle?atoms), what would happen to the particle? Their path will not change (according to Their path will not change (according to

Thomson’s plum pudding)Thomson’s plum pudding)

4.14.1 Studying Atoms – Gold Foil Studying Atoms – Gold Foil ExperimentExperiment

4.1 The Gold Foil Experiment4.1 The Gold Foil Experiment

all atoms positive charge is concentrated in the nucleusall atoms positive charge is concentrated in the nucleus

RUTHERFORD’S ATOMIC THEORYRUTHERFORD’S ATOMIC THEORY

4.14.1 Studying Atoms – Modern Atomic Studying Atoms – Modern Atomic TheoryTheory

Bohr Atom:Bohr Atom: focused on the focused on the electronselectrons

Electrons are in energy levelsElectrons are in energy levelsThey move when the atom gains or loses They move when the atom gains or loses energyenergy

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. Work on the “Bohr Model” Worksheet Work on the “Bohr Model” Worksheet

from the back table. Use the Periodic from the back table. Use the Periodic Table to help you.Table to help you.

FILL IN THE Parts of an ATOM:FILL IN THE 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 MASSthe ATOMIC MASS

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-): Current Theory – Current Theory – “Electron Cloud Model” (p116-17)“Electron Cloud Model” (p116-17)

Shows POSSIBLE locations of electrons around nucleusShows POSSIBLE locations of electrons around nucleus It’s a good approximation of how electrons behaveIt’s a good approximation of how electrons behave

Electrons (e-):Electrons (e-): ORBITALS: ORBITALS: the most likely location the most likely location

of the electrons in the cloud.of the electrons in the cloud.

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