Chemistry | Chapters Seven & Eight

metallic bonds

"Nomadic electrons" A foa caused by sharing loosely held valence electrons among many metal ions. Like a sea of electrons moving among the metal ions.

ductility

Able to be drawn into a wire

malleability

Able to be spread

valence electrons; helium; two

Electrons in the outermost energy level. Same as the roman number group number ("A" groups only). _______ is an exception to the group number - only has ____.

transferred; shared

Electrons may be _______ or ________ - this is what distinguishes the type of bond

expanded octets

Have axial and equatorial positions. Axial positions cause *more* repulsion than equatorial (EQ is 90 degreees from two domains while axial is 90 degrees from three)

Carbon Family

Have four bonds.

Nitrogen bonds

Have three bonds

Oxygen Family

Have two bonds

covalently bonded

A molecule is two or more atoms _____________ _________ - *do not have to be different kinds of atoms.*

molecules with >2 atoms

Geometry is determined by the number of pairs of electrons around the centeral atom.

valence shell electron pair repulsion

What does VSEPR stand for?

same

Not all bonds are the _____

polyatomic ions

Groups of covalently bonded atoms that act like ions because they have the wrong number of electrons.

pure covalence; diatomic

Has perfect sharing. This occurs when the en = 0. ________ elements have pure covalent bonds

alloys

Mixture of metals. *These are not compounds*

gain; negative

Nonmetals ______ electrons to fill their valence shells, making them _______ ions.

gain

Nonmetals ________ electrons to complete their octet.

equally; more

Not all atoms share electrons _______. Some attract electrons _____ than others.

lone pairs; greater

Not pulled by two atoms so they stay closer to the central atom. Have a ______ repulsion than bonding pairs and strongly affect the molecule shape

coordination number

Number of oppositely charged ions surrounding one ion in the crystal.

He:

Helium's dot structure.

break

Old bonds ________ before new bonds form.

phase, melting/boiling point, viscosity, density, solubility

Properties affected by van der waals forces

valence number

*Charge* on cation or anion

expanded octet

> 8 electrons on the central atom. *Only applies to period three elements and beyond* C, N, O, and F never have an expanded octet

chemically bonded

A compound is two or more different atoms _____________ __________.

polar covalent bond; stronger

A covalent bond is which en is > 0.5 is called this. Unequal sharing is great enough to have a positive end and a negative end Negative end is at the atom with the higher en. The greater the difference in en, the ________ the polarity.

covalent bonds; ionic;

A foa due to sharing one or more pairs of valence electrons. Each atom usually contributes one electron for each pair. Causes temporary chargers that result in attraction. *These are weaker than ______ bonds.*

ionic bond

A foa due to the transfer of one or more valence electrons from one atom to another.

chemical bond

A force of attraction (*foa*) between atoms due to opposite charges

individual constituents

Alloys often have superior properties to the _________ _____________.

lone pairs in expanded octets

Always occupy equatorial positions when there are five domains. Can occupy any position when there are six domains since all of them are alike.

steel

An alloy of iron and carbon and other metals added depending on application.

domains

Bonding and non-bonding electrons establish _____ around the central atom.

four bonds

Bonding rules for ions: Boron and Carbon Family have...

one bond

Bonding rules for ions: H and Halogens have....

two, three, and four bonds

Bonding rules for ions: N Family have...

one, two, and three bonds

Bonding rules for ions: O Family have...

ionic compound properties

Brittle solids at room temperature. High melting points. Separate into ions (dissociate) when dissolved in water. Aqueous solutions conduct electricity (electrolytes)

formal charges

Difference between number of e- of each atom has the Lew structure and its valence e- Always occur in ions.

ionic compound

Charges cancel so it is neutral Arranged in regular repeating patterns called crystal (*not molecules*)

positive

Coordinate covalent bond is present anytime there is _________ formal charge.

steps for ions

Count total valence e- (add charge of anion, subtract charge of cation). Others are the same Use arrangements that minimize formal charges.

molecular

Covalent bonds result in a compound called _________.

six steps (molecules without charges)

Determine Octet e- How many electrons do they want? Count total valence e- How many do they have? Subtract these to get bonding e- Divide bonding e- by two to determine number of bonds. Subtract bonding e- from valence e- to determine number of lone pairs then add them to the structure. Draw arrangement putting atom that forms the most bonds in the middle (no rings)

3 kinds of van der waal forces

Dipole interactions, London dispersion forces, hydrogen bonds

IA, IIA, IIIA

Elements in ____ become +1, ____ become +2, and _____ become +3.

VIIA, VIA, VA

Elements in _____ become -1, _____ become -2, and ____ become -3.

Octet Rule; noble gases

Elements tend to react so that they end up with eight valence electrons (like ________ ________).

non-polar covalent

En < 0.5 Unequal sharing is so little that positive and negative ends are not significant.

bond dissociation energy

Energy input required to break a bond. *Endothermic* Strong bonds require large energies Expressed in kJ/mol

dipole interactions

Forces between polar molecules. Similar to ionic bonds, but they are weaker - more distant. MIDDLE STRENGTH

negative; positive

Formal charges - Atoms with more e- are _________. Atoms with fewer e- are _________. If nonequivalent structures exist, those with smallest formal charges and have most electronegative atom as negative best represent molecule.

share; react

IV (4A) tends to _____ electrons, and VIII (8A) doesn't ______.

ionic

If the difference in en is > 2.0 then the bond is called....

covalent

If the en is < 2.0 then the bond is called....

types of chemical bonds

Ionic, Covalent, and Metallic

opposite charges; ionic

Ions attract due to the _________ __________ (electrostatic forces). This results in a compound called an _______ compound.

molecular geometry

Lew structure shows how atoms are bonded, but do not show the correct type of this. Molecules with only two atoms can be linear.

electronegativity; 0 to 4

Meaure of an atom's attraction for electrons in a covalent bond. Greater is stronger. Rated on a scale from _____

crystalline structures of metals; body; face; hexagonal

Metal atoms arranged in one of three compact patterns: ____ centered cubic ____ centered cubic __________ close packing

Luster, Conductivity, Malleability, and Ductility

Metallic Properties

lose; positive

Metals _____ all valence electrons making them _______ ions.

lose

Metals ______ electrons to reveal a lower energy level with an octet.

intermolecular forces; melting points

Molecular compounds have weak _______________ _______ allowing them to be gases or liquids with low boiling points. They can also be crystalline solids that have low _________ ________

network solids; diamond and SiC

Molecular substance in which all atoms are covalently bonded. _______ and ________ are examples. Very HIGH melting points

intermolecular attraction forces

Molecules tend to position themselves to minimize repulsion forces and maximize attraction forces between molecules. Leads to net attraction forces between them called Van Der Waal forces.

resonance

Molecules with > 1 correct Lew structure. e- Shift between these arrangements, so the molecule is best represented by the average of them.

polar molecules

Molecules with polar bonds and a geometry that allows poles to occur. Also called *dipoles* Polarity affects physical properties.

greater; distort

Multiple bonds have _______ repulsion force than single bonds and ______ symetry

formula unit; neutral

Name of the simplest ratio of ions in an ionic compound (since they do *not* form molecules). Based on valence numbers. Number of each ion is whatever is needed to make it ______.

molecular compounds

Neutral Form molecules Do not dissociate in water (may or may not dissolve) Usually not electrolytes

london dispersion foces

Occur due to asymmetrical distribution of electrons creating temporary polarity of atoms or molecules. WEAKEST Van Der Waal force, but can be quite strong in large atoms or molecules. Only force between noble gas atoms.

hydrogen bonds

Occur when hydrogen is bonded to a very electronegative atom and attracted to a lone pair in a nearby atom H must be bonded to N, O, or F. Other atoms don't have a high enough en. STRONGEST van der waal force.

single bonds

One pair of electrons is shared Atoms that only need one electron to complete its valence shell. One atom may form several single bonds if it needs more than one electron.

valence shell

Outermost (highest) energy level that contains electrons in the ground state. Largest value of n (principal quantum number) in electron config.

vsepr theory; different

Repulsion between electron pairs around an atom cause them to take positions as far as possible to minimize repulsion forces. Bonding pairs and lone pairs have _____ effects.

electron dot structures (lewis structures)

Shared (bonding) electrons shown as a line between atoms. Non-bonding electrons (lone pairs) shown as pairs of dots.

octet rule in covalent bonding

Sharing occurs so that all atoms obtain eight valence electrons. This may require sing, double, or triple covalent bonds

triple bond

Sharing three pairs of electrons between atoms is a ________ _________.

double bond

Sharing two pairs of electrons between two atoms is a ________ _________.

dot structure rules

Show element symbol Use 4 sides: top, right bottom, left Only two dots per side 1st dot goes on any side. Remaining dots arranged one per side until you have to double.

electron dot structures

Show only valence electrons as dots.

molecular formulas

Shows how many atoms of each element in a molecule. Subscripts may not be simplest ratio. *Do not show bonding arrangement*

electrical conduction

Since electrons are free to move as electrons come in on end, other electrons leave.

durable

Sterling silver is more _________ than pure silver.

polarity

Symmetry is the enemy to....

hydrogen (H), nitrogen (N), oxygen (O), fluorine (F), chlorine (Cl), bromine (Br), and iodine (I)

The seven diatomic elements are.....

coordinate covalent bond

The shared pair of electrons comes from one atom. The other atom does not contribute an electron for this bond. May occur for one of the bonds in a multiple bond. Once formed, it acts like any other covalent bond

seven

There are _______ diatomic elements.

Hydrogen and Halogens

These have one bond

Boron

Three bonds (weird). No desire to get eight valence electrons.

diatomic molecule

Two atoms of the *same* element covalently bonded.

electrically neutral

Valence numbers are used to determine formulas of ionic compounds so they are ____________ ____________.

polar

When electrons are not shared equally, the bond is called ______.

nonpolar

When electrons are shared equally, the bond is called ______.

notation

molecules that have a centeral atom bonded to two or more atoms of the same kind can be described by a notation of the form AB#N# A is the *central* atom B is the number or atoms bonded to A N is the number of non-bonding (lone) pairs on A

exceptions to octet rule

odd number of electrons < an octet > an octet *cannot handle at all*