warm up iron can form two different oxides ….. fe 2 o 3 and feo. we know for absolute certainty...
TRANSCRIPT
Warm Up
Iron can form two different oxides ….. Fe2O3 and FeO. We know for absolute certainty that an oxygen anion always has a -2 charge. What is going on here … how can there be two iron oxides???
Warm Up-Answer
-Turns out we need to balance charges such that compound has zero charge
- So in FeO if we have 1 oxygen atom that is always a -2 charge then (1 O atom)(-2) = -2 …..
so then our Fe must have a +2 charge to balance out (1 Fe atom)(+2) = +2 …. +2 and -2 cancel out
-With Fe2O3 we have (3 O atoms)(-2) = -6So (2 Fe)(???) = +6The answer is of course +3 ….
Warm Up - Answer
FeO has a +2 charged iron cationFe2O3 has a +3 charged iron cation
Ion Formation and Naming Ions
Chapter 7.1/9.1
Learning Objectives• You will know what valence electrons are and how
to determine how many.
• You will be able to draw electron dot structures of 1A-8A elements
• You will understand the octet rule and how it leads to stable cations and anions
• You will learn how to name simple anions and cations
• You will understand how to name transition metals and polyatomic ions
Valence Electrons
–Electrons in the highest occupied energy level (s and p only)
–Determines chemical properties of element–Equals the group number (A series)– Involved in chemical bonding
Lewis Dot Structures
–Diagrams that show the valence electrons of an atom using dots
–Also called electron dot structures
Octet Rule
– Atoms tend to gain, lose, or share electrons until they are surrounded by eight valence electrons
– Goal to be isoelectronic to a noble gas
Special Vocabulary
Isoelectronic–Ions that have the same electron
configuration
Halide ions–When the halogen group elements
become ions (F-, Cl-, Br-, I-)
Monoatomic Ions
Single atom with a positive or negative charge. Occurs when lose (cation) or gain (anion) valence electrons
1A 2A 3A 4A 5A 6A 7A 8A
Li+ Be2+ B3+ N3- O2- F-
Na+ Mg2+ Al3+ P3- S2- Cl-
K+ Ca2+ As3- Se2- Br-
Rb+ Sr2+ I-
Cs+ Ba2+
Naming Cations
Naming of cation usually involves the name of the element plus the word ion
Na+ would be called sodium ion
–Alternative techniques for variable charge ions (transition elements)
Naming Transition Metal Ions
Symbol Modern name
Cu+ Copper(I) ion
Cu2+ Copper(II) ion
Fe2+ Iron(II) ion
Fe3+ Iron(III) ion
Sn2+ Tin(II) ion
Sn4+ Tin(IV) ion
A few transition metals only have one charge and roman numerals are not used … Ag+, Cd2+, Zn2+
Naming Anions
Naming of anion– Monatomic anion ends in –ide
Not chlorine … chloride
Not oxygen … oxide
Not nitrogen … nitride
– Many anions are polyatomic – need to memorize the more common ones … chart I gave you today.
Polyatomic Anions
Ions that are composed of more than one atom. Most are anions (negative charge).
SO42-
sulfateThe names of most polyatomic anions end in –ite or –ate.
Homework
Chapter 7.1 (Read!!) page 193 (#3-9) page 207-208 (#31,32, 62)
Chapter 9.1 (Read!!)page 258 (#4,5,8,9) page 281 (#42-46)