atoms and bonding chapter 5. atomic structure and the periodic table review the structure of the...
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Atoms and BondingChapter 5
Atomic Structure and the Periodic TableReview the structure of the atomProtons?Neutrons?Electrons?Nucleus?Electron Cloud?
P+NProtons (+)Neutron (0)Electron (-)Valence electrons
Atomic Structure and the Periodic Table (cont)Electrons (negative) move around the nucleus in the electron cloud. The electron cloud has different energy shells (or orbits). In a neutral atom the number of electrons equals the number of protons.
Atomic Structure and the Periodic Table (cont)Valence electrons are the electrons in the outer shell.
The valence electrons determine which elements combine to form compounds!
Why do Elements Form Compounds?1. Atoms combine to complete the outer energy shell of electrons2. A complete outer energy shell is stable. (atoms with filled outer energy shells wont combine with other atoms)
Why do Elements Form Compounds? 3. shell #1 it is complete with 2 electrons.
4. Shells # 2-7 are complete with 8 electrons
What happens when a chemical bond is formed?A chemical bond is the force of attraction that holds atoms together A new substance is formed in a chemical reactionproperties of the new substance are different than the properties of the elements that make them upElectrons are gained, given away or shared
Electron Dot DiagramsShows valence electrons only
Uses dots to represent electrons
Can be used to show how elements bond
Chemical FormulaChemical Formula - A shorthand way to write the name of the compound
What information does a chemical formula contain?
Metals METALS are on the left side of the Periodic Table. They have a low number of valence electrons and can easily give them to other atoms.
Almost empty shells
NonmetalsB. NONMETALS are on the right side of the Periodic Table. They have a high number of valence electrons and can easily take or share valence electrons from other atoms
Almost full shells
Semi MetalsC. SEMIMETALS are found between metals and nonmetals along the zigzag line. They can either lose or share valence electrons with other atoms
About half full shell
Ionic BondsION- a charged particle; atoms either gain or lose electrons to form:A. Positive Ions form when atoms lose electrons (more protons than electrons)B. Negative Ions form when atoms gain electrons (more electrons than protons)
Ionic BondsMetal to nonmetal
Transfer of electrons from one atom to the other
How does an ionic bond form? 1.Metals lose electrons and form positive ions. Nonmetals gain electrons and form negative ions.
2. Ions with opposite charges attract each other (+ and attract)
Properties of ionic compoundsVery strong bonds Form crystal lattice (alternating, repeating)hard, brittle solids with high boiling and melting points, conduct electricity when dissolved in water.
Naming Ionic Compoundsname the positive ion (metal) firstname the negative ion (nonmetal) next with the ending changed to ideNaCl: sodium + chlorine = sodium chloride
Name these:K2S: Potassium + sulfur = potassium sulfide Li2O: lithium + oxygen = lithium oxideMg3P2Magnesium + phosphorous = magnesium phosphide
Covalent bondsForm nonmetal to nonmetal
How does a covalent bond form?atoms share electrons to fill outer energy shells (it takes too much energy to transfer electrons)
the force that holds atoms together in a covalent bond is the attraction of each atoms nucleus for the shared pair of electrons
Properties of covalent compoundsWeak bondslow melting & boiling pointsMany are gases and liquidscannot conduct electricity when dissolved in water
moleculea neutral group of atoms held together by a covalent bond; smallest piece of a compound
Covalent compounds are also called molecular compounds
Diatomic Elements:An element that bonds with itself to form the simplest of molecules.There are only 7 elements that are diatomic.H, N, O, F, Cl, Br, I
XI. Naming covalent compounds Use prefixes:Mono = 1Di = 2Tri = 3Tetra = 4Penta = 5Hexa = 6
Carbon dioxideCO2Carbon monoxideCODihydrogen monoxideH20
Metallic Bondsmetal to metal
Positive metal ions swimming in sea of released electrons
How does a metallic bond form?Metals tend to lose electrons and form positive ions. The bonds are held together by the force of attraction between positive metal ions and the many electrons surrounding them.
Metallic bondmetal atoms combine in regular patterns which allow the electrons to move from atom to atom
Alloymixture of 2 or more elements, at least 1 is a metalstronger and less reactive than pure metals. Properties of alloys are different from the pure metals that make them up
Metallic bond: mixture or chemical bond(honors slide)Alloys are a mixture because they can be in any ratioAlloys are like a chemical bond because they have different properties than the metals that form themAlloys are like a chemical bond because the electrons are interacting
Properties of MetalsDenseshinySolids at room temperature (except Mercury)malleableductile Good conductors of heat and electricity
Number scratch paper from 1-10Cross out number 8
Write the answer to fill in the blank
A simplified slide