Class Notes (972,785)
CA (572,895)
AU (542)
CHEM (12)
CHEM 217 (12)
kate (12)
Lecture 3

CHEM 217 Lecture 3: Unit 3
Premium

by OneClass933557 , Spring 2018
11 Pages
62 Views

Department
Chemistry
Course Code
CHEM 217
Professor
kate
Lecture
3

This preview shows pages 1-3. Sign up to view the full 11 pages of the document.
Unit 3
3. 1
Compound properties generally very different from the properties of the elements
Law of definite proportions applies to compounds not mixtures
3. 2 BO N D S
Result of interactions between charged particles
Ionic bonds
oMetal lose (e-) to nonmetals
oElectrostatic forces make oppositely charged ions attracted to each other
oAs multiple ions pairs form, they can group together and th result is an ionic compound in the
solid phase composed of a lattice
Covalent bonds
oNonmetal & nonmetal
oNo transfer of electrons. Insteadm they share them
oShared electrons interact with both nuclei which loewers potential anergy of one system through
electrostatic interactions
oMolecular compound, composed of individually bound covalent molecules
oUnderstand stability of a covalent bond by considering the most stable/lowest potential energy
configuration of a negative charge interacting with two positive charges
oShowed that electrons hold the bonding atoms toether by attracting positively harged nuclei of
both
3. 3 R E P R E S EN T I NG CO M P O U N D S
Easiest way: chemical formula : indicates elements present in the compounds and the relative numbering
of atoms or ions of each
oUsually list the more metallic (or more positively charged ) elements first followed by less
metallic (or more negatively charged ones)
Types of formulas
oEmpirical formula
Gives relative # of atoms of each element in a compound
oMolecular formula
find more resources at oneclass.com
find more resources at oneclass.com
Gives actual # of atoms of each element in a compound
Ex. hydrogen peroxide
oEmpirial – HO
oMolecular H2O2
Molecular always a whole-number multiple of the empirical and for some compounds they are the same
A structural formula uses lines to represent covalent bonds and shows how atoms in a molecule are
connected
oAlso may be written to give asense of geometry
oStrucural can also depict types of bonds
Structural formula conveys the most information while empricial conveys the least
Elements can be atomic or molecular// compounds can be molecular, ionic
oAtomic elements – exist in nature with single atom basic units, most elements
oMolecular elements – exist as molecules – two or more atoms of the element bound together
oMolecular compounds are two or more covalently bound nonmetals. Basic units are molecules
composed of constituent atoms
oIonic compounds – made of cations (usualy one type of metal) and anions (1 or more nonmetals)
bound ionically
Basic unit is formula unit, the smallest, electrically neutral collection of ions and do not
exist as discrete entities but as a part of a large lattice
Many common ionic compounds contain ions that are composed of a group of
covalently bound atoms with an overall charge
3. 4 FO R MU L A & NA M ES
Common names – no info conveyed about composition
Systematic names – more info
Ionic compounds – occur through earth’s crust as minerals. Generally stable because of cation/anion
interactions
Writing formulas for ionic compounds
oSince they’re charge-neutral and since many elements ofrm only one type of ion with a
predictable charge, the formulas for many ionic compounds can be deduced from their
constituent elements
oSummary
Always contain positive and negative ions
Sum of the charges must be equal to the sum of the negative ions and of the positive
ions
find more resources at oneclass.com
find more resources at oneclass.com
A formula reflects the smallest whole number ratio of ions
Procedure for writing ionic compounds
o1. Write the symbol for the metal cation and its charge, followed by the symbol for the non-
metal anion and its charge. Obtain charges from the elements group # in table
o2. Adjust subscript on each cation and anion to balance overall charge
o3. Check that the sum of the charges of the cations equals the sum of the charges of the anions
Naming ionic compounds
oFor metals that form cations with one possible charge, the name is just the metal
oFor metals that form cations with more than 1 possible charge, the name is metal followed by
the charge in roman numerals in brackets, this Fe2+ is Iron (II), etc.
oNames for nonatomic anions consist of base name of the element followed by suffix-ide
oIonic compounds with a polyatomic ion are named the same way but with the name of the
polyatomic ion
oIf the compound contains both a polyatomic cation and polyatomic anion, noth are named
Ex. NH4NO3
Most polyatomic ions are oxyanions – anions containing oxygen and another element
oWhen oxyanions contain different numbers of oxygen atoms, they are named systematically
according to # of O in the ion.
If there are only two ions in the series, the one with more oxygen atoms has ending
ate and the one with fewer has ending –ite.
Ex. NO3 - Nitrate
Ex. NO2 – Nitrite
If there are more than 2 ions in the series, the prefixes hypo- meaning less than and per-
meaning more than are used.
EX. ClO- is hypochlorite (less oxygenthan chlorite) and ClO4- is perchlorate (more
oxygen than chlorate)
Hydrated ionic compounds
oSome ionic compounds called hydrates have a specific # of water molecules associated with each
formula unit
oThe H2O molecules are waters of hydration – they can usually be removed by heating the
compound
oHydrates are named just as other ionic compounds but they are given additional name “prefix
hydrate” where the prefix indicates the # of water molecules associated with each formula unit
Written as:
find more resources at oneclass.com
find more resources at oneclass.com

Loved by over 2.2 million students

Over 90% improved by at least one letter grade.

Leah — University of Toronto

OneClass has been such a huge help in my studies at UofT especially since I am a transfer student. OneClass is the study buddy I never had before and definitely gives me the extra push to get from a B to an A!

Leah — University of Toronto
Saarim — University of Michigan

Balancing social life With academics can be difficult, that is why I'm so glad that OneClass is out there where I can find the top notes for all of my classes. Now I can be the all-star student I want to be.

Saarim — University of Michigan
Jenna — University of Wisconsin

As a college student living on a college budget, I love how easy it is to earn gift cards just by submitting my notes.

Jenna — University of Wisconsin
Anne — University of California

OneClass has allowed me to catch up with my most difficult course! #lifesaver

Anne — University of California
Description
Unit 3 3.1 Compound properties generally very different from the properties of the elements Law of definite proportions applies to compounds not mixtures 3.2 BONDS Result of interactions between charged particles Ionic bonds o Metal lose (e-) to nonmetals o Electrostatic forces make oppositely charged ions attracted to each other o As multiple ions pairs form, they can group together and th result is an ionic compound in the solid phase composed of a lattice Covalent bonds o Nonmetal & nonmetal o No transfer of electrons. Insteadm they share them o Shared electrons interact with both nuclei which loewers potential anergy of one system through electrostatic interactions o Molecular compound, composed of individually bound covalent molecules o Understand stability of a covalent bond by considering the most stable/lowest potential energy configuration of a negative charge interacting with two positive charges o Showed that electrons hold the bonding atoms toether by attracting positively harged nuclei of both 3.3 REPRESENTING COMPOUNDS Easiest way: chemical formula : indicates elements present in the compounds and the relative numbering of atoms or ions of each o Usually list the more metallic (or more positively charged ) elements first followed by less metallic (or more negatively charged ones) Types of formulas o Empirical formula Gives relative # of atoms of each element in a compound o Molecular formula Gives actual # of atoms of each element in a compound Ex. hydrogen peroxide o Empirial HO o Molecular H2O2 Molecular always a whole-number multiple of the empirical and for some compounds they are the same A structural formula uses lines to represent covalent bonds and shows how atoms in a molecule are connected o Also may be written to give asense of geometry o Strucural can also depict types of bonds Structural formula conveys the most information while empricial conveys the least Elements can be atomic or molecular// compounds can be molecular, ionic o Atomic elements exist in nature with single atom basic units, most elements o Molecular elements exist as molecules two or more atoms of the element bound together o Molecular compounds are two or more covalently bound nonmetals. Basic units are molecules composed of constituent atoms o Ionic compounds made of cations (usualy one type of metal) and anions (1 or more nonmetals) bound ionically Basic unit is formula unit, the smallest, electrically neutral collection of ions and do not exist as discrete entities but as a part of a large lattice Many common ionic compounds contain ions that are composed of a group of covalently bound atoms with an overall charge 3.4 FORMULA & NAMES Common names no info conveyed about composition Systematic names more info Ionic compounds occur through earths crust as minerals. Generally stable because of cation/anion interactions Writing formulas for ionic compounds o Since theyre charge-neutral and since many elements ofrm only one type of ion with a predictable charge, the formulas for many ionic compounds can be deduced from their constituent elements o Summary Always contain positive and negative ions Sum of the charges must be equal to the sum of the negative ions and of the positive ions A formula reflects the smallest whole number ratio of ions Procedure for writing ionic compounds o 1. Write the symbol for the metal cation and its charge, followed by the symbol for the non- metal anion and its charge. Obtain charges from the elements group # in table o 2. Adjust subscript on each cation and anion to balance overall charge o 3. Check that the sum of the charges of the cations equals the sum of the charges of the anions Naming ionic compounds o For metals that form cations with one possible charge, the name is just the metal o For metals that form cations with more than 1 possible charge, the name is metal followed by the charge in roman numerals in brackets, this Fe is Iron (II), etc. o Names for nonatomic anions consist of base name of the element followed by suffix-ide o Ionic compounds with a polyatomic ion are named the same way but with the name of the polyatomic ion o If the compound contains both a polyatomic cation and polyatomic anion, noth are named Ex. NH 4O 3 Most polyatomic ions are oxyanions anions containing oxygen and another element o When
More Less
Unlock Document

Only pages 1-3 are available for preview. Some parts have been intentionally blurred.

Unlock Document
You're Reading a Preview

Unlock to view full version

Unlock Document

Log In


OR

Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit