ions and ionic bonding. an ion is an atom, or group of atoms, that has a net positive or negative...
TRANSCRIPT
Ions and Ionic Bonding
An ion is an atom, or group of atoms, that has a net positive or negative charge.
cation – ion with a positive chargeIf a neutral atom loses one or more electronsit becomes a cation.
anion – ion with a negative chargeIf a neutral atom gains one or more electronsit becomes an anion.
Na 11 protons11 electrons
Na+ 11 protons10 electrons
Cl 17 protons17 electrons
Cl- 17 protons18 electrons
2.5
A monatomic ion contains only one atom
A polyatomic ion contains more than one atom
2.5
Na+, Cl-, Ca2+, O2-, Al3+, N3-
OH-, CN-, NH4+, NO3
-
13 protons, 10 (13 – 3) electrons
34 protons, 36 (34 + 2) electrons
Do You Understand Ions?
2.5
How many protons and electrons are in Al2713
?3+
How many protons and electrons are in Se7834
2- ?
2.5
Objectives
Review Valence Electrons, Lewis Dot Structures, and Noble Gas Configurations
Objectives
Discuss, compare, and contrast the different types of ions and ionic bonding
Convert atoms to ionsExplore metallic bondingDiscuss naming of compoundsExplore the geometry of ionic and metallic bonding
2.6
A molecular formula shows the exact number of atoms of each element in the smallest unit of a substance
An empirical formula shows the simplest whole-number ratio of the atoms in a substance
H2OH2O
molecular empirical
C6H12O6 CH2O
O3 O
N2H4 NH2
2.6
ionic compounds consist of a cation and an anion• the formula is always the same as the empirical formula
• the sum of the charges on the cation and anion in each formula unit must equal zero
The ionic compound NaCl
2.6
Ionic Bonding
No sharing of electronsAtoms become ions and fulfill the octet ruleThere is still an attraction (electrostatic forces)
between the ions so they stay together in a specific arrangement – ionic bondThis arrangement has more to do with geometry than
anything though
Ionic Bonding
Typically, ionic bonding occurs when a cation and an anion exchange electron(s). This forms what is commonly called a salt.
What happens in ionic bonding
Polyatomic ions that you need to know(Quiz Next Week)
Name Formula
Name Formula
Ammonium NH4+ Sulfate SO4
2-
Hydroxide OH- Phosphate PO43-
Carbonate CO32- Chlorate ClO3
-
Nitrate NO3- Chromate CrO4
2-
Permanganate MnO4- Acetate C2H3O2
-
Chemical NomenclatureIonic Compounds
often a metal + nonmetal
anion (nonmetal), add “ide” to element name
BaCl2 barium chloride
K2O potassium oxide
Mg(OH)2 magnesium hydroxide
KNO3 potassium nitrate
2.7
Transition metal ionic compounds
indicate charge on metal with Roman numerals
FeCl2 2 Cl- -2 so Fe is +2 iron(II) chloride
FeCl3 3 Cl- -3 so Fe is +3 iron(III) chloride
Cr2S3 3 S-2 -6 so Cr is +3 (6/2) chromium(III) sulfide
2.7
Bellringer – Chemistry AgendaNotes on Ionic
Bonds QuestionsNotes on
Metallic Bonds + properties
Begin Metallic Bonding
Lab tomorrow if finished with notes
• Clear Targets• I can explain how ionic and
metallic bonds are formed• I can relate the physical properties
of metals and alloys to their chemical make up.
• Polyatomic Ion Quiz Tomorrow• Paper Due 15th.
Ionic Bonding
Chemical Formula – shows the kinds and numbers of atoms in the smallest representative sample
Formula unit – the formula using the lowest whole number ratio of ions in an ionic compound
Properties of Ionic Compounds
Most ionic compounds are crystalline solids at room temperatureHave high melting pointsCan conduct electricity when melted
or dissolved in water
Coordination number – the number of ions of the opposite charge that surround the ion in a crystalSurrounded by 6 ions of the
opposite charge – CN = 6
Bellringer – Chemistry
AgendaBellringer
(5min)Notes on Ionic
Bonds QuestionsNotes on
Metallic Bonds + properties
Begin Metallic Bonding
Lab tomorrow if finished with notes
• Clear Targets• I can explain how ionic and
metallic bonds are formed• I can relate the physical properties
of metals and alloys to their chemical make up.
• Polyatomic Ion Quiz Tomorrow• Paper Due 15th.
Metallic Bonding
Metallic Bonding
Metals are not made up of neutral atoms’
They are rather closely packed cations The valence electrons of these metal atoms act
like a sea of electrons (they are mobile and can drift)This explains conductivity (electrons flow)
It also explains ductility and malleability ( the positive ions can flow around. In a non metal they cannot move away from each other, so when the positive ions are in each other’s presence the compound shatters)
Metallic Bonds consist of these electrons being attracted to the positive metallic ions
Bellringer – Chemistry
AgendaBellringer
(5min)Notes on Ionic
Bonds QuestionsNotes on
Metallic Bonds + properties
Begin Metallic Bonding
Lab tomorrow if finished with notes
• Clear Targets• I can explain how ionic and
metallic bonds are formed• I can relate the physical properties
of metals and alloys to their chemical make up.
• Polyatomic Ion Quiz Tomorrow• Paper Due 15th.
Crystalline Structure of Metals
Most metals are arranged in very compact and orderly patterns. Body Centered Cubic – every
atom has eight neighborsFace Centered Cubic – every
atom has 12 neighborsHexagonal Close Packed - every
atom has 12 neighbors (but in a different way)
Bellringer – Chemistry
AgendaBellringer
(5min)Notes on Ionic
Bonds QuestionsNotes on
Metallic Bonds + properties
Begin Metallic Bonding
Lab tomorrow if finished with notes
• Clear Targets• I can explain how ionic and
metallic bonds are formed• I can relate the physical properties
of metals and alloys to their chemical make up.
• Polyatomic Ion Quiz Tomorrow• Paper Due 15th.
Alloys
Alloys – mixture of elements where at least one is a metal This is done because often the properties of the alloys are superior to the metal itself
Substitutional Alloy – an alloy where one of the parts of the crystalline structure is replaced by another element (happens when the atoms are of similar sizes)
Interstitial Alloy – an alloy where the atoms are of different sizes and the new atom fits into the spaces (interstices) between the larger atoms.
Bellringer – Chemistry
AgendaBellringer
(5min)Notes on Ionic
Bonds QuestionsNotes on
Metallic Bonds + properties
Begin Metallic Bonding
Lab tomorrow if finished with notes
• Clear Targets• I can explain how ionic and
metallic bonds are formed• I can relate the physical properties
of metals and alloys to their chemical make up.
• Polyatomic Ion Quiz Tomorrow• Paper Due 15th.
