B.8-B.9 In which you will learn about: Atomic number & mass number Ions Naming ionic compounds

An atom consists of a nucleus nucleus – (of protons and neutrons) electrons in space about the nucleus. electrons in space about the nucleus. 8.5 The Electrical Nature of Matter Nucleus Electron cloud

Copper atoms on silica surface. An atom is the smallest particle of an element that has the chemical properties of the element. An atom is the smallest particle of an element that has the chemical properties of the element. Distance across = 1.8 nanometer (1.8 x m)

Subatomic Particles Quarks – component of protons & neutrons – 6 types –3 quarks = 1 proton or 1 neutron He

ATOM COMPOSITION protons and neutrons in the nucleus.protons and neutrons in the nucleus. the number of electrons is equal to the number of protons.the number of electrons is equal to the number of protons. electrons in space around the nucleus.electrons in space around the nucleus. extremely small. One teaspoon of water has 3 times as many atoms as the Atlantic Ocean has teaspoons of water.extremely small. One teaspoon of water has 3 times as many atoms as the Atlantic Ocean has teaspoons of water. The atom is mostly empty space

ATOMIC COMPOSITION Protons (p + ) Protons (p + ) – + electrical charge – mass = x g – relative mass = atomic mass units (amu) but we can round to 1 Electrons (e - ) Electrons (e - ) – negative electrical charge – relative mass = amu but we can round to 0 Neutrons (n o ) Neutrons (n o ) – no electrical charge – mass = amu but we can round to 1

Atomic Number, Z All atoms of the same element have the same number of protons in the nucleus, Z 13 Al Atomic number Atom symbol AVERAGE Atomic Mass

Mass Number, A C atom with 6 protons and 6 neutrons is the mass standard C atom with 6 protons and 6 neutrons is the mass standard = 12 atomic mass units = 12 atomic mass units Mass Number (A) = # protons + # neutrons Mass Number (A) = # protons + # neutrons NOT on the periodic table…(it is the AVERAGE atomic mass on the table) NOT on the periodic table…(it is the AVERAGE atomic mass on the table) A boron atom can have A = 5 p + 5 n = 10 amu A boron atom can have A = 5 p + 5 n = 10 amu

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 form mass 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, 12 C, 13 C, and 14 C. State the number of protons, neutrons, and electrons in each of these carbon atoms. 12 C 13 C 14 C #p + _______ _______ _______ #n o _______ _______ _______ #e - _______ _______ _______

B.9 Ions and Ionic Compounds IONS are atoms or groups of atoms with a positive or negative charge. IONS are atoms or groups of atoms with a positive or negative charge. Taking away an electron from an atom gives a CATION with a positive charge Taking away an electron from an atom gives a CATION with a positive charge Adding an electron to an atom gives an ANION with a negative charge. Adding an electron to an atom gives an ANION with a negative charge. To tell the difference between an atom and an ion, look to see if there is a charge in the superscript! Examples: Na + Ca +2 I - O -2 vs. Na Ca I O To tell the difference between an atom and an ion, look to see if there is a charge in the superscript! Examples: Na + Ca +2 I - O -2 vs. Na Ca I O

Forming Cations & Anions A CATION forms when an atom loses one or more electrons. An ANION forms when an atom gains one or more electrons Mg --> Mg e- F + e- --> F -

PREDICTING ION CHARGES In general metals (Mg) lose electrons ---> cations metals (Mg) lose electrons ---> cations nonmetals (F) gain electrons ---> anions nonmetals (F) gain electrons ---> anions

Learning Check – Counting State the number of protons, neutrons, and electrons in each of these ions. 39 K + 16 O -241 Ca #p + ___________________ #n o ___________________ #e - ___________________

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

Forms of Chemical Bonds There are 3 forms bonding atoms:There are 3 forms bonding atoms: Ionic—complete transfer of 1 or more electrons from one atom to another (one loses, the other gains)Ionic—complete transfer of 1 or more electrons from one atom to another (one loses, the other gains) Covalent—some valence electrons shared between atomsCovalent—some valence electrons shared between atoms Metallic – holds atoms of a metal togetherMetallic – holds atoms of a metal together Most bonds are somewhere in between ionic and covalent.

Common Names A lot of chemicals have common names as well as the proper IUPAC name. A lot of chemicals have common names as well as the proper IUPAC name. Chemicals that should always be named by common name and never named by the IUPAC method are: Chemicals that should always be named by common name and never named by the IUPAC method are: – H 2 Owater, not dihydrogen monoxide – NH 3 ammonia, not nitrogen trihydride

CATION + ANION ---> COMPOUND COMPOUND CATION + ANION ---> COMPOUND COMPOUND A neutral compound requires equal number of + equal number of + and - charges. A neutral compound requires equal number of + equal number of + and - charges. COMPOUNDS FORMED FROM IONS Na + + Cl - --> NaCl

Predicting Charges on Monatomic Ions KNOW THESE !!!! Cd +2

Properties of Ionic Compounds Forming NaCl from Na and Cl 2 A metal atom can transfer an electron to a nonmetal. A metal atom can transfer an electron to a nonmetal. The resulting cation and anion are attracted to each other by electrostatic forces. The resulting cation and anion are attracted to each other by electrostatic forces.

IONIC COMPOUNDS NH 4 + Cl - ammonium chloride, NH 4 Cl

Some Ionic Compounds Mg 2+ + N > Mg 3 N 2 magnesium nitride Sn 4+ + O > SnO 2 Tin (IV) oxide calcium fluoride Ca F - ---> CaF 2

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: = 0

Monatomic Ions

Writing a Formula Write the formula for the ionic compound that will form between Ba 2+ and Cl . Solution: 1. Balance charge with + and – ions 2. Write the positive ion of metal first, and the negative ion Ba 2+ Cl  Cl  3. Write the number of ions needed as subscripts BaCl 2

Learning Check Write the correct formula for the compounds containing the following ions: 1. Na +, S 2- a) NaS b) Na 2 Sc) NaS 2 2. Al 3+, Cl - a) AlCl 3 b) AlCl c) Al 3 Cl 3. Mg 2+, N 3- a) MgN b) Mg 2 N 3 c) Mg 3 N 2

Naming Compounds 1. Cation first, then anion 2. Monatomic cation = name of the element Ca 2+ = calcium ion 3. Monatomic anion = root + -ide Cl  = chloride CaCl 2 = calcium chloride Binary Ionic Compounds:

Naming Binary Ionic Compounds Examples: NaCl ZnI 2 Al 2 O 3 sodium chloride zinc iodide aluminum oxide

Learning Check Complete the names of the following binary compounds: Na 3 Nsodium ________________ KBrpotassium________________ Al 2 O 3 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 or 3+ Cu +, Cu 2+ Fe 2+, Fe 3+ 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. FeCl 3 (Fe 3+ ) iron (III) chloride CuCl (Cu + ) copper (I) chloride SnF 4 (Sn 4+ ) tin (IV) fluoride PbCl 2 (Pb 2+ )lead (II) chloride Fe 2 S 3 (Fe 3+ )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: FeBr 2 iron (_____) bromide CuClcopper (_____) chloride SnO 2 ___(_____ ) ______________ Fe 2 O 3 ________________________ Hg 2 S________________________

NO 3 - nitrate ion NO 2 - nitrite ion Polyatomic Ions

You can make additional polyatomic ions by adding a H + to the ion! CO 3 -2 is carbonate HCO 3 – is hydrogen carbonate H 2 PO 4 – is dihydrogen phosphate HSO 4 – is hydrogen sulfate Polyatomic Ions

Ternary Ionic Nomenclature Writing 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 Compounds Contains at least 3 elements There MUST be at least one polyatomic ion (it helps to circle the ions) Examples: NaNO 3 Sodium nitrate K 2 SO 4 Potassium sulfate Al(HCO 3 ) 3 Aluminum bicarbonate or Aluminum hydrogen carbonate

Ternary Ionic Nomenclature Sodium Sulfate Na + and SO 4 -2 Na 2 SO 4 Iron (III) hydroxide Fe +3 and OH - Fe(OH) 3 Ammonium carbonate NH 4 + and CO 3 –2 (NH 4 ) 2 CO 3

Learning Check 1. aluminum nitrate a) AlNO 3 b) Al(NO) 3 c) Al(NO 3 ) 3 2. copper(II) nitrate a) CuNO 3 b) Cu(NO 3 ) 2 c) Cu 2 (NO 3 ) 3. Iron (III) hydroxide a) FeOHb) Fe 3 OHc) Fe(OH) 3 4. Tin(IV) hydroxide a) Sn(OH) 4 b) Sn(OH) 2 c) Sn 4 (OH)

Learning Check Match each set with the correct name: 1. Na 2 CO 3 a) magnesium sulfite MgSO 3 b) magnesium sulfate MgSO 4 c) sodium carbonate 2.Ca(HCO 3 ) 2 a) calcium carbonate CaCO 3 b) calcium phosphate Ca 3 (PO 4 ) 2 c) calcium bicarbonate

Mixed Practice! Name the following: 1.Na 2 O 2.CaCO 3 3.PbS 2 4.Sn 3 N 2 5.Cu 3 PO 4 6.HgF 2

Mixed Up… The Other Way Write the formula: 1.Copper (II) chlorate 2.Calcium nitride 3.Aluminum carbonate 4.Potassium bromide 5.Barium fluoride 6.Cesium hydroxide