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Difference between atoms and ions
- Atoms are a singular unit. when it has a charge it becomes an ion.
- an atom can be an ion, but not all ions are atoms.
- when an atoms outermost orbital gains or loses an electron, it becomes an ion.
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difference between molecules and polyatomics
The difference between regular molecules and polyatomic ions is that polyatomic ions have a charge on the entire molecule as a whole.
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difference between covalent and ionic bonds
- Covelent: results from two atoms sharing electrons usually between two non metals
- Ionic: electrostatic attraction between charged particles after a complete transfer of electrons from one atom to another. usually between non metal and a metal.
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what substances occur as a diatomic molecule? (7)
H2, N2, O2, F2, Cl2, Br2, and I2
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what elements tend to gain electrons and form _____?
Non metals; anions
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What elements tend to lose electrons and form ____?
Metals; cations
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what is the definition of the ground state electron configuration for atoms?
lowest energy configuration
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What are the relative size trends?
- across a period- radius increases
- Down a column- radius gets smaller
- (biggest at bottom left, smallest at upper right)
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What are the trends for Ionization energy (Ei)?
- across a period, Ei gets greater
- down a column, Ei gets smaller
- exceptions for group 2A
- (greatest at noble gases, lowest at lower left)
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what is Ionization energy (Ei)?
the amount of energy necessary to remove the highest energy electron from an isolated neutral atom in the gaseous state
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What is electron affinity (Eea)?
- the energy that occurs when an electron is added to an atom
- (favorable)
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What are the trends for electron Affinity?
- Highest affinity at halogens (F, Cl, Br, I, At) because greatest E lost.
- greater going right.
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what does it mean when Eea=0?
energy is required but amount is NOT known
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What is the octet rule?
- lowest energy orbitals fill first
- opposite spins
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Noble gas configurations.
Ex. Na
Na: [Ne] 3s1
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Born-Haber calculations
Ex. NaCl
- Na(s)--> Na(g) +E change
- 1/2 Cl2--> Cl(g) +E change
- Na(g)--> Na+(g) +e- +E change
- Cl(g)+e- -->Cl-(g) -E change
- Na+(g)+Cl-(g)-->NaClg -E change
overall reaction is negative, favorable.
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What are lattice energies? (U)
the amount of energy required to break up an ionic solid to individual gasous atoms.
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trends of lattice method
- as radii goes up, the easier it is to break the bonds of electrons
- as charge goes up (ex. 2+, 3+) the U goes up
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Molecule vs. Compound
- Molecule: a unit of matter held together by covalent bonds
- Compound: a pure chemical substance consisting of 2 or more elements
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electronegativity and relation to types of bonds
- e-negativity >1.7 ionic bonds
- e-negativity=.4-1.7 polar covalent
- e-negativity <.4 nonpolar covalent bond
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electronegativity trends
- across a row: electronegativity increases
- down a column: electronegativity decreases
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electronegativity's relation to Ei and Eea
- as Ei goes up, e-neg goes down
- as Eea goes up, e-neg goes up
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Prefixes
- Mono-1
- di-2
- tri-3
- tetra-4
- penta-5
- hexa-6
- hepta-7
- octa-8
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what is a lewis dot structure?
a representation of an atoms valence e-, by using dots. the placement of the dots is related to the e- are located.
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what are resonance structures? what are the rules?
- same connectivity, different arrangements of electrons
- Rules:
- minimize formal charges to make equal. 0>1>2
- charges on more electronegative atoms are best
- S=C=N- is better than S-=C=N
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lewis structure for sulfate
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Lewis structure for ammonium
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Lewis structure for acetate
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lewis structure for cyanide
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lewis structure for hydroxide
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lewis structure for nitrate
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lewis structure for carbonate
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lewis structure for phosphate
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lewis structure for oxalate
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VSEPR
valence shell electron pair repulsion
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VSEPR definition
bonds are an area with a high concentration of negative charge. negative charges repel eachother and bonds want to be as far away from one another.
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what is the geometric and molecular shape of a molecule with a charge cloud of 2?
- Linear for both
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what is the geometric and molecular shape of a molecule with a charge cloud of 3?
- Trigonal Planar for both
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what is the geometric and molecular shape of a molecule with a charge cloud of 4 with no lone pairs?
- Tetrahedral for both
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what is the geometric and molecular shape of a molecule with a charge cloud of 4 with one lone pair?
- Tetrahedral for e-
- trigonal pyramidal for molecular geo
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what is the geometric and molecular shape of a molecule with a charge cloud of 4 with two lone pairs.
- Tetrahedral for E- geo
- Bent for molecular geo.
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Sigma and Pi bond definition
- sigma: overlap of singular e-
- pi: sideways bond overlap above/below Sigma bond.
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Octohedral bonds are made with __ electron pairs
- 6
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square pyramidal geometry is made with __ electron pairs
- 5
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what molecules do not need a full octet?
Aluminum and Boron only need 3
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describe the formation of sp3hybrid orbitals and identify which atoms use sp3hybridization to form bonds
- single bonded atoms (i.e. CH4)
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describe the formation of sp2hybrid orbitals and identify which atoms use sp2hybridization to form bonds
- Double bonded atoms (i.e. C2H2)
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describe the formation of sp hybrid orbitals and identify which atoms use sp hybridization to form bonds
- triple bonded atoms (i.e. C2H2)
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