B.8-B.9

In which you will learn about:•Atomic number & mass number

•Ions•Naming ionic compounds

An atom consists of a An atom consists of a • nucleus nucleus

– (of (of protons protons and and neutronsneutrons) ) • electrons electrons in space about the nucleus.in space about the nucleus.

8.5 The Electrical Nature of Matter8.5 The Electrical Nature of Matter

NucleusNucleus

Electron cloudElectron cloud

Copper Copper atoms on atoms on silica silica surface.surface.

• AnAn atomatom is the smallest particle of an is the smallest particle of an element that has the chemical properties of element that has the chemical properties of the element.the element.

Distance across = 1.8 nanometer (1.8 x 10-9 m)

Subatomic ParticlesSubatomic Particles

• Quarks– component of component of

protons & protons & neutronsneutrons

– 6 types6 types

– 3 quarks = 3 quarks = 1 proton or 1 proton or 1 neutron1 neutron

He

ATOM ATOM COMPOSITIONCOMPOSITION

•protons and neutrons in protons and neutrons in the nucleus.the nucleus.

•the number of electrons is equal to the number of the number of electrons is equal to the number of protons.protons.

•electrons in space around the nucleus.electrons in space around the nucleus.

•extremely small. One teaspoon of water has 3 extremely small. One teaspoon of water has 3 times as many atoms as the Atlantic Ocean has times as many atoms as the Atlantic Ocean has teaspoons of water.teaspoons of water.

The atom is mostlyThe atom is mostlyempty spaceempty space

ATOMIC COMPOSITIONATOMIC COMPOSITION• Protons (pProtons (p++))

– + electrical charge+ electrical charge– mass = 1.672623 x 10mass = 1.672623 x 10-24-24 g g– relative mass = 1.007 atomic mass units relative mass = 1.007 atomic mass units

(amu) (amu) but we can round to 1but we can round to 1• Electrons (eElectrons (e--))

– negative electrical chargenegative electrical charge– relative mass = 0.0005 amu relative mass = 0.0005 amu but we can round but we can round

to 0to 0• Neutrons (nNeutrons (noo))

– no electrical chargeno electrical charge– mass = 1.009 amu mass = 1.009 amu but we can round to 1but we can round to 1

Atomic Number, ZAtomic Number, ZAll atoms of the same element have All atoms of the same element have

the same number of protons in the the same number of protons in the nucleus, nucleus, ZZ

1313

AlAl

26.98126.981

Atomic numberAtomic number

Atom symbolAtom symbol

AVERAGE Atomic MassAVERAGE Atomic Mass

Mass Number, AMass Number, A• C atom with 6 protons and 6 neutrons is the C atom with 6 protons and 6 neutrons is the

mass standard mass standard • = 12 atomic mass units= 12 atomic mass units• Mass NumberMass Number (A) (A)

= # protons + # neutrons= # protons + # neutrons• NOT on the periodic table…(it is the AVERAGE NOT on the periodic table…(it is the AVERAGE

atomic mass on the table)atomic mass on the table)• A boron atom can have A boron atom can have A A

= 5 p + 5 n = 10 amu = 5 p + 5 n = 10 amu

A

Z

10

5B

A

Z

10

5B

Atomic Symbols

Show the name of the element, a hyphen, and the

mass number in hyphen notation

sodium-23

Show the mass number and atomic number in

nuclear symbol formmass number 23 Na

atomic number 11

Counting Protons, Neutrons, and Electrons

• Protons: Atomic Number (from periodic table)• Neutrons: Mass Number minus the number of

protons (mass number is protons and neutrons because the mass of electrons is negligible)

• Electrons: – If it’s an atom, the protons and electrons must be the SAME

so that it is has a net charge of zero (equal numbers of + and -)

– If it does NOT have an equal number of electrons, it is not an atom, it is an ION. For each negative charge, add an extra electron. For each positive charge, subtract an electron (Don’t add a proton!!! That changes the element!)

Learning Check – Counting

Naturally occurring carbon consists of three isotopes, 12C, 13C, and 14C. State the number of protons, neutrons, and electrons in each of these carbon atoms.

12C 13C 14C 6 6 6

#p+ _______ _______ _______

#no _______ _______ _______

#e- _______ _______ _______

B.9 Ions and Ionic B.9 Ions and Ionic CompoundsCompounds

• IONSIONS are atoms or groups of atoms with a positive or are atoms or groups of atoms with a positive or negative charge. negative charge.

• Taking awayTaking away an electron from an atom gives a an electron from an atom gives a CATIONCATION with a with a positive chargepositive charge

• AddingAdding an electron to an atom gives an an electron to an atom gives an ANIONANION with a with a negative chargenegative charge..

• To tell the difference between an atom and an ion, look to To tell the difference between an atom and an ion, look to see if there is a charge in the superscript! Examples: Nasee if there is a charge in the superscript! Examples: Na++ CaCa+2+2 I I-- O O-2 -2 vs. Na Ca I Ovs. Na Ca I O

Forming Cations & AnionsForming Cations & AnionsForming Cations & AnionsForming Cations & Anions

A A CATIONCATION forms forms when an atom loses when an atom loses one or more one or more electrons.electrons.

An An ANIONANION forms forms when an atom when an atom gains one or more gains one or more electronselectrons

Mg --> Mg2+ + 2 e- F + e- --> F-

PREDICTING ION CHARGESPREDICTING ION CHARGESPREDICTING ION CHARGESPREDICTING ION CHARGES

In generalIn general

• metalsmetals (Mg) (Mg) lose electrons lose electrons ---> ---> cationscations

• nonmetalsnonmetals (F) (F) gain electronsgain electrons ---> ---> anionsanions

Learning Check – Counting

State the number of protons, neutrons, and electrons in each of these ions.

39 K+ 16O -2 41Ca +2

19 8 20

#p+ ______ ______ _______

#no ______ ______ _______

#e- ______ ______ _______

Charges on Common Charges on Common IonsIons

Charges on Common Charges on Common IonsIons

-1-2-3+1

+2

By losing or gaining e-, atom has same number of By losing or gaining e-, atom has same number of e-’s as nearest Group 8A (noble gas) atom.e-’s as nearest Group 8A (noble gas) atom.

Forms of Chemical Bonds

• There are 3 forms bonding There are 3 forms bonding atoms:atoms:

• IonicIonic—complete —complete transfer transfer of 1 or of 1 or more electrons from one atom more electrons from one atom to another (one loses, the other to another (one loses, the other gains)gains)

• CovalentCovalent——some valence some valence electrons electrons sharedshared between between atomsatoms

• MetallicMetallic – holds atoms of a – holds atoms of a metal togethermetal together

Most bonds are Most bonds are somewhere in somewhere in between ionic between ionic and covalent.and covalent.

Common Names• A lot of chemicals have common A lot of chemicals have common

names as well as the proper IUPAC names as well as the proper IUPAC name.name.

• Chemicals that should always be Chemicals that should always be named by common name and never named by common name and never named by the IUPAC method are:named by the IUPAC method are:– HH22OO water, not dihydrogen water, not dihydrogen

monoxidemonoxide– NHNH33 ammonia, not nitrogen ammonia, not nitrogen

trihydridetrihydride

CATIONCATION + + ANIONANION ---> --->

COMPOUNDCOMPOUND

CATIONCATION + + ANIONANION ---> --->

COMPOUNDCOMPOUND

A neutral compound A neutral compound requiresrequires

equal number of + equal number of + and - charges.and - charges.

A neutral compound A neutral compound requiresrequires

equal number of + equal number of + and - charges.and - charges.

COMPOUNDS FORMED

FROM IONS

COMPOUNDS FORMED

FROM IONSNaNa++ + Cl + Cl- - --> NaCl--> NaCl

Predicting Charges on Monatomic IonsPredicting Charges on Monatomic IonsKNOW THESE !!!!KNOW THESE !!!!

+1 +2 -3 -2 -1 0

Cd+2

Properties of Ionic CompoundsProperties of Ionic CompoundsForming NaCl from Na and ClForming NaCl from Na and Cl22

Properties of Ionic CompoundsProperties of Ionic CompoundsForming NaCl from Na and ClForming NaCl from Na and Cl22

• A metal atom can A metal atom can transfer an electron to transfer an electron to a nonmetal.a nonmetal.

• The resulting cation The resulting cation and anion are and anion are attracted to each other attracted to each other by by electrostatic electrostatic forcesforces..

IONIC COMPOUNDSIONIC COMPOUNDS

NH4+

Cl-

ammonium chloride, NHammonium chloride, NH44ClCl

Some Ionic CompoundsSome Ionic Compounds

MgMg2+2+ + N + N-3-3 ----> ---->MgMg33NN22

magnesiummagnesium nitridenitrideSnSn4+4+ + O + O2-2- ----> ----> SnOSnO22

Tin (IV) oxideTin (IV) oxide

calcium fluoridecalcium fluoride

CaCa2+2+ + 2 F + 2 F-- ---> ---> CaFCaF22

Formulas of Ionic Compounds

Formulas of ionic compounds are determined from the charges on the ions

atoms ions

–Na + F : Na+ : F : NaF

sodium + fluorine sodium fluoride formula

Charge balance: 1+ 1- = 0

Monatomic Ions

Writing a Formula

Write the formula for the ionic compound that will form between Ba2+ and Cl.

Solution:1. Balance charge with + and – ions 2. Write the positive ion of metal first, and the

negative ion Ba2+ Cl Cl

3. Write the number of ions needed as

subscripts BaCl2

Learning Check

Write the correct formula for the compounds containing the following ions:1. Na+, S2-

a) NaS b) Na2S c) NaS2

2. Al3+, Cl-

a) AlCl3 b) AlCl c) Al3Cl3. Mg2+, N3-

a) MgN b) Mg2N3 c) Mg3N2

Naming CompoundsNaming Compounds

• 1. Cation first, then anion

• 2. Monatomic cation = name of the element

• Ca2+ = calcium ion

• 3. Monatomic anion = root + -ide• Cl = chloride

• CaCl2 = calcium chloride

Binary Ionic Compounds:Binary Ionic Compounds:

Naming Binary Ionic Compounds

Examples:NaCl

ZnI2

Al2O3

sodium chloride

zinc iodide

aluminum oxide

Learning Check

Complete the names of the following binary compounds:Na3N sodium ________________

KBr potassium ________________

Al2O3 aluminum ________________

MgS _________________________

Transition Metals

Elements that can have more than one possible charge

MUST have a Roman Numeral to indicate the charge

on the individual ion.

1+ or 2+ 2+ or 3+

Cu+, Cu2+ Fe2+, Fe3+

copper(I) ion iron(II) ion copper (II) ion iron(III) ion

Names of Variable Ions

These elements REQUIRE Roman Numerals because they can have more than one possible charge:anything except Group 1A, 2A, Ag, Zn, Cd, and Al

(You should already know the charges on these!)

Or another way to say it is: Transition metals and the metals in groups 4A and 5A (except Ag, Zn, Cd, and Al) require a Roman Numeral.

FeCl3 (Fe3+) iron (III) chlorideCuCl (Cu+ ) copper (I) chlorideSnF4 (Sn4+) tin (IV) fluoridePbCl2 (Pb2+) lead (II) chloride

Fe2S3 (Fe3+) iron (III) sulfide

Examples of Older Names of Cations formed from Transition Metals

(you do not have to memorize these)

Learning Check

Complete the names of the following binary compounds with variable metal ions:

FeBr2 iron (_____) bromide

CuCl copper (_____) chloride

SnO2 ___(_____ ) ______________

Fe2O3 ________________________

Hg2S ________________________

NONO33--

nitrate ionnitrate ion

NONO22--

nitrite ionnitrite ion

Polyatomic IonsPolyatomic Ions

You can make additional polyatomic You can make additional polyatomic ions by adding a Hions by adding a H++ to the ion! to the ion!

COCO33 -2-2 is carbonate is carbonate

HCOHCO33–– is hydrogen carbonate is hydrogen carbonate

HH22POPO44–– is dihydrogen phosphate is dihydrogen phosphate

HSOHSO44–– is hydrogen sulfate is hydrogen sulfate

Polyatomic IonsPolyatomic Ions

Ternary Ionic NomenclatureWriting Formulas

• Write each ion, cation first. Don’t show charges in the final formula.

• Overall charge must equal zero.– If charges cancel, just write symbols.– If not, use subscripts to balance charges.

• Use parentheses to show more than one of a particular polyatomic ion.

• Use Roman numerals indicate the ion’s charge when needed (stock system)

Naming Ternary CompoundsContains at least 3 elementsThere MUST be at least one polyatomic ion

(it helps to circle the ions)Examples:

NaNO3 Sodium nitrate

K2SO4 Potassium sulfateAl(HCO3)3 Aluminum bicarbonate

or Aluminum hydrogen carbonate

Ternary Ionic NomenclatureSodium SulfateNa+ and SO4 -2

Na2SO4

Iron (III) hydroxideFe+3 and OH-

Fe(OH)3

Ammonium carbonateNH4

+ and CO3 –2

(NH4)2CO3

Learning Check

1. aluminum nitrate a) AlNO3 b) Al(NO)3 c) Al(NO3)3

2. copper(II) nitrate a) CuNO3 b) Cu(NO3)2 c) Cu2(NO3)

3. Iron (III) hydroxide

a) FeOH b) Fe3OH c) Fe(OH)3

4. Tin(IV) hydroxide

a) Sn(OH)4 b) Sn(OH)2 c) Sn4(OH)

Learning Check

Match each set with the correct name:1. Na2CO3 a) magnesium sulfite

MgSO3 b) magnesium sulfate

MgSO4 c) sodium carbonate

2 . Ca(HCO3)2 a) calcium carbonate

CaCO3 b) calcium phosphate

Ca3(PO4)2 c) calcium bicarbonate

Mixed Practice!Name the following:1. Na2O

2. CaCO3

3. PbS2

4. Sn3N2

5. Cu3PO4

6. HgF2

Mixed Up… The Other Way

Write the formula:1. Copper (II) chlorate2. Calcium nitride3. Aluminum carbonate4. Potassium bromide5. Barium fluoride6. Cesium hydroxide