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This chapter discusses electron arrangements, electron dot diagrams, and different types of chemical bonds, such as ionic and covalent bonds. Practice creating electron dot diagrams and naming ionic compounds.
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Chemical Bonding Chapter 1 Interactions of Matter
REVIEW • Identify the 4 atoms whose models are on the bulletin board. • How did you identify these elements?
Electron Arrangements Remember electrons arrange in energy levels outside the nucleus.
Electron Dot Diagrams • Show ONLY outer level electrons • Also called Lewis diagrams • Begin with the element’s symbol • Use the PT to determine the number of outer level electrons • Place up to 2 dots per side for a total of up to 8 electrons • Put the first 2 dots together on one side, then put single dots on the remaining sides until you have to pair them
Electron Dot Diagrams • Ex: 1 electron X
Electron Dot Diagrams • Ex: 2 electrons X
Electron Dot Diagrams • Ex: 3 electrons X Choose a clockwise or counterclockwise direction and fill empty sides with an electron before pairing any electrons.
Electron Dot Diagrams • Ex: 4 electrons X Choose a clockwise or counterclockwise direction and fill empty sides with an electron before pairing any electrons.
Electron Dot Diagrams • Ex: 5 electrons X Choose a clockwise or counterclockwise direction and fill empty sides with an electron before pairing any electrons.
Electron Dot Diagrams • Ex: 6 electrons X Choose a clockwise or counterclockwise direction and fill empty sides with an electron before pairing any electrons.
Electron Dot Diagrams • Ex: 7 electrons X Choose a clockwise or counterclockwise direction and fill empty sides with an electron before pairing any electrons.
Electron Dot Diagrams • Ex: 8 electrons X THIS IS THE MOST ELECTRONS THAT EVER ARE INCLUDED IN ELECTRON DOT DIAGRAMS.
Electron Dot Diagrams • Time to practice what you’ve learned • For the following elements, create electron dot diagrams using M&M’s as electrons. Be sure to write large size symbols on your paper. • YUM, but no eating allowed until all your work is checked and is correct! BRING IN YOUR ATOMIC MODEL TOMORROW!
CHEMICAL BONDING • The number of electrons in the ____________ energy level determines whether an atom will form bonds. • These electrons are also called ___________ electrons. • Atoms bond to get a ________ outer level. • For all E levels beyond the first, the outermost E level is considered to be full if it contains ______ (#) electrons. • The first E level is full with ____ (#) electrons. • Why are noble gases nonreactive?
CHEMICAL BONDING • Atoms bond by __________, ____________, or ___________ electrons to have a filled outermost energy level containing 8 valence electrons. • ___(#) types of bonds hold atoms together. • IONIC BOND- force of electrostatic attraction between 2 oppositely charged ______. • Ions form when electrons are _________________. • COVALENT BOND- force of attraction between nuclei of atoms and the electrons _______________ by the atoms. • Neutral atoms held by covalent bonds are called __________________. • METALLIC BOND- force of attraction between a ____________ charged metal ion and the electrons in a metal.
IONIC BONDS • Chem 4 Kids example • METALS • have a low/high number of valence electrons. • metals lose/gain electrons when bonding. • form positive/negative ions. • NONMETALS • have a low/high number of valence electrons. • lose/gain electrons when bonding. • form positive/negative ions. • ions end in –ide
Naming IONIC compounds Binary compounds- contain only 2 elements • negative ion ends in -ide • Ex: Name NaCl • Ex: Name AlF3 • Ex: Name Li2S • compounds are neutral so use subscripts to make (+)=(-) • Write the chemical formula for • Ex: strontium sulfide • Ex: potassium oxide • Ex: calcium chloride • Ex: barium nitride
Naming IONIC compounds Binary compounds- containing transition elements • Transition metals- the charge is in parenthesis following the name of the metal except for Ag, Cd, and Zn (see PT) • ex: chromium (II) chloride • ex: iron (III) oxide • Ex: NiF2 vs. NiF • Ex: CrI4 vs. CrI2
Naming IONIC compounds What about compounds with more than 2 elements • Look on page 159 for polyatomic ions • Polyatomic ions- groups of atoms that are bonded together with a charge • Usually end in -ate • Ex: BaSO4 • Ex: potassium phosphate • Ex: iron (III) carbonate
IONIC BONDS- metal ion + nonmetal ion • CHARACTERISTICS OF IONIC COMPOUNDS • Hard, brittle solids at room temp • High melting and boiling points • Ions are held in a crystal lattice • Conduct electricity when dissolved in H2O
Quick Review Barium sulfide Aluminum carbonate NaClO3 SiO2 Dinitrogenpentoxide
COVALENT BONDS • Unlike ionic bonds with transferred electrons, covalent bonds __________ electrons. IONIC BOND COVALENT BOND
COVALENT BONDS • Unlike ionic bonds that generally form between metals and nonmetals, covalent bonds form between ________________. • Classify the bonds as ionic or covalent • Na-Cl • H-O • C-O • Ca-F • N-N • Cr-S NOTE: Group 14 has a strange e-dot diagram
COVALENT BONDS • Use electron dot diagrams to model molecules • Examples: • H2 • H2O • NH3 • Cl2
COVALENT BONDS • Some molecules are simple with only one element • 7 elements are not found in nature as atoms • They always are found in pairs- called diatomic N2 O2 F2 And H2 (always the exception) Cl2 Br2 I2
COVALENT BONDS • EXAMPLES OF COVALENT COMPOUNDS • water • plastic • sugar • Gasoline oils & fats • CHARACTERISTICS OF COVALENT COMPOUNDS • Do NOT conduct an electrical current • Low melting and boiling points • Lightweight molecules: generally gases and liquids at room temp • Heavier molecules: generally solids at room temp
COVALENT COMPOUNDS • Naming covalent compounds involves using prefixes to indicate the number of atoms in the formula. • Website w/prefixes and rules
COVALENT COMPOUNDS • When atoms share electrons, they don’t always share them equally. • Nonpolar covalent compounds: share e- equally • Will not conduct an electrical current at all • All diatomic molecules are nonpolar • Polar covalent compounds: share e- unequally • Can conduct an electrical current
COVALENT COMPOUNDS • Polarity affects how chemicals mix. • “Like dissolves like.” • Nonpolar compounds mix with other nonpolar compounds. • Ex: • Polar compounds mix with other polar compounds. • Ex: • Nonpolar compounds will not mix with polar compounds. • Ex: • How does this affect how soap is made?
METALLIC BONDS • EXAMPLES CONTAINING METALLIC BONDS • Cu, Fe • Alloys- mixtures of metals • EX: brass, bronze, steel • CHARACTERISTICS OF METALS • Malleable & ductile • Good conductors • “sea of electrons” allows metals to be shaped without breaking • Close metal atoms have overlapping outer E levels • Valence electrons can move freely between positive metal ions