Unit 3: The AtomUnit 3: The Atom

AtomsAtoms

All matter is made of very tiny All matter is made of very tiny particlesparticlesThese particles have the same These particles have the same

properties as the matter hasproperties as the matter has

Parts of the AtomParts of the Atom

Subatomic Particles – smaller Subatomic Particles – smaller than an atomthan an atom

ProtonProtonNeutronNeutronElectronElectron

Subatomic ParticlesSubatomic Particles

ProtonsProtonsPositive chargePositive chargeEach one has a charge of +1Each one has a charge of +1Located in the nucleusLocated in the nucleusEach one has a mass of 1amu Each one has a mass of 1amu (atomic mass unit)(atomic mass unit)

Subatomic ParticlesSubatomic Particles

NeutronsNeutronsNo chargeNo chargeLocated in the nucleusLocated in the nucleusEach one has a mass of 1amu Each one has a mass of 1amu (atomic mass unit)(atomic mass unit)

Subatomic ParticlesSubatomic Particles

ElectronsElectronsNegative chargeNegative chargeEach one has a charge of -1Each one has a charge of -1Located in the space around the Located in the space around the nucleusnucleus

Each one has a mass of about Each one has a mass of about 0.0006amu (atomic mass unit)0.0006amu (atomic mass unit)

The AtomThe Atom

The AtomThe Atom

The nucleus has protons and The nucleus has protons and neutronsneutronsPositively chargedPositively charged

The electron cloud has electronsThe electron cloud has electronsNegatively chargedNegatively charged

The number of protons equals the The number of protons equals the number of electrons in a neutral atomnumber of electrons in a neutral atom

Periodic TablePeriodic Table

The periodic table gives us lots of The periodic table gives us lots of information about the elements.information about the elements.

1

H

Hydrogen

1.008

Atomic Number

Element Symbol

Element Name

Average Atomic Mass

Symbol PracticeSymbol Practice

For the element name, give the symbol.For the element name, give the symbol.HeliumHeliumCarbonCarbonSulfurSulfurOxygenOxygenMagnesiumMagnesium

Element PracticeElement Practice

For the symbol, give the element name.For the symbol, give the element name.LiLiNNArArAlAlNaNa

Atomic NumberAtomic Number

Atoms of different elements are Atoms of different elements are differentdifferent

All protons and neutrons are identical All protons and neutrons are identical to each otherto each other

The number of protons in the nucleus The number of protons in the nucleus explains the differenceexplains the difference

The number of protons in the nucleus The number of protons in the nucleus is the atomic number of an elementis the atomic number of an element

Atomic NumberAtomic Number

The atomic number identifies the The atomic number identifies the elementelement

Like DNA for an elementLike DNA for an elementExamples:Examples:

Hydrogen atoms and only hydrogen Hydrogen atoms and only hydrogen atoms have 1 proton in the nucleusatoms have 1 proton in the nucleus

Helium atoms and only helium atoms Helium atoms and only helium atoms have 2 protons in the nucleushave 2 protons in the nucleus

Proton PracticeProton Practice

Practice: How many protons are in Practice: How many protons are in each of the following elements?each of the following elements?CarbonCarbonPotassium Potassium NitrogenNitrogenCalcium Calcium SiliconSilicon

ElectronsElectrons

Electrons give atoms their chemical Electrons give atoms their chemical propertiesproperties

In order for an atom to have a neutral In order for an atom to have a neutral charge, it must have the same charge, it must have the same number of electrons as it has protons.number of electrons as it has protons.

Electrons = protons = atomic numberElectrons = protons = atomic number

Electron PracticeElectron Practice

Practice: How many electrons are in Practice: How many electrons are in each of the following elements?each of the following elements?HeliumHeliumChlorine Chlorine NitrogenNitrogenAluminum Aluminum BoronBoron

Mass NumberMass Number

All atoms have a mass numberAll atoms have a mass numberWe can figure it out by rounding the We can figure it out by rounding the

Average Atomic Mass to the nearest Average Atomic Mass to the nearest whole numberwhole number

Mass number = protons + neutronsMass number = protons + neutronsNeutrons = Mass number – protonsNeutrons = Mass number – protons

Finding NeutronsFinding NeutronsExample: CarbonExample: CarbonRound the Average Atomic Mass to Round the Average Atomic Mass to

the nearest whole number: the nearest whole number: 12.01 rounds to 1212.01 rounds to 12

How many protons in carbon?How many protons in carbon?66

Neutrons = Mass number – protonsNeutrons = Mass number – protonsNeutrons = 12 – 6 = 6Neutrons = 12 – 6 = 6

Neutron PracticeNeutron Practice

Practice: How many neutrons are in Practice: How many neutrons are in each of the following elements?each of the following elements?OxygenOxygenChlorine Chlorine ArgonArgonAluminum Aluminum PhosphorusPhosphorus

Atom Concept MapAtom Concept Map

First 25 Elements ActivityFirst 25 Elements Activity

IsotopesIsotopes

Isotopes of an element have the Isotopes of an element have the same number of protons, but different same number of protons, but different numbers of neutrons.numbers of neutrons.

There can be many isotopes of the There can be many isotopes of the same element.same element.