Chem Unit 4

What is an octet

8 valence electrons

How are chemical bonds formed?

by the attraction between the positive nucleus of one atom and the negative electrons of another atom

positively charged ion

cation

negatively charged ion

anion

Why are metals reactive?

because they lose valence electrons easily

What are binary ionic compounds?

compounds that contain two different elements, a metallic cation and a nonmetallic anion

What is a crystal lattice

a three-dimensional geometric arrangement of particles

Can solid ionic compounds conduct electricity?

No, the electrons cannot flow freely

Can liquid ionic compounds conduct electricity?

Yes, they have electrons that are free to move

What is an ion in an aqueous solution that conducts electricity called?

Electrolyte

What are reactions that absorb energy called?

endothermic

What are reactions that release energy called?

exothermic

What is lattice energy?

The energy required to separate 1 mol of ions in an ionic compound

the smaller the ion the \________ the lattice energy

greater

Smaller the ion \______ the attraction

greater

How are atoms formatted in ionic compounds?

Cation is first, then the anion

What is a formula unit?

The simplest ratio of the ions involved

What are monatomic ions?

one atom ions

oxidation number

the charge of a monatomic ion

polyatomic ions are

ions made of more than one atom

What must the total charge equal in an ionic compound?

0

What are the diatomic elements?

hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, iodine

(Have No Fear Of Ice Cold Beer.)

Oxyanion

a polyatomic ion that contains oxygen

What are the steps in naming ionic compounds?

1. Name the cation followed by the anion

2. For monatomic cations use the element name

3. For monatomic anions, use the root element name and the suffix - ide

4. The oxidation state is written in parentheses after the name of the cation

5. When the compound contains a polyatomic ion, name the cation followed by the name of the polyatomic ion.

What is a mettalic bond?

The attraction of an metallic cation for delocalized electrons

What is the electron sea model?

proposes that all the metal atoms in a metallic solid contribute their valence electrons to form a "sea" of electrons

delocalized electrons

the electrons involved in metallic bonding that are free to move easily from one atom to the next throughout the metal and are not attached to a particular atom

Are boiling points more or less extreme then melting points?

They are more extreme

What are the properties of metals?

They are malleable and ductile

Malleable

capable of being shaped

Ductable

Can be drawn into wires

What are alloys?

substances made from two or more different metals mixed together

What are substitutional alloys?

Formed when some atoms in the original metallic solid are replaced by other metals of similar atomic structure

What does metal conduct?

heat and electricity

As the number of delocalized electrons in a metal increases...

The hardness and strength of the metal increases

covalent bond

A chemical bond that involves sharing a pair of electrons between atoms in a molecule

What is a molecule?

A group of 2 or more atoms bonded together

Why do atoms bond?

To become more stable

What is the strongest bond?

covalent bond

What is a Lewis structure?

a molecular representation that shows both the connections among atoms and the locations of lone-pair valence electrons

What are sigma bonds?

single covalent bonds

When do sigma bonds occur?

when the pair of shared electrons is in an area centered between the two atoms

What are double bonds?

when atoms share two pairs of electrons

What are triple bonds?

When atoms share three pairs of electrons

What is a multiple covalent bond?

when two atoms share more than one pair of electrons

What is a pi bond?

It is formed when parallel orbitals overlap and share electrons

When do pi bonds occur?

double and triple bonds

What is bond dissociation energy?

the energy required to break the bond between two covalently bonded atoms

The shorter the bond length the \_______ the bond dissociation energy

greater

As length of the bond increases, the strength of the bond \___.

decreases

What is an endothermic reaction?

A greater amount of energy is required to break a bond in reactants than is released when the new bonds form in the product

What is an exothermic reaction?

A reaction where more energy is released than is required to break the bonds in the initial reactants

How do you name binary molecular / covalent compounds?

1. The first element is always named first using the entire element name

2. The second element is named using its root and adding the suffix - ide

How do you name mono atomic acids?

- The first word has the prefix hydro - followed by the root of the element plus the suffix - ic

- The second world is always acid

What is an oxyacid?

an acid that is a compound of hydrogen and an oxyanion

How are oxyacids named?

- The first word is the root of the oxyanion and the prefix per- or hypo- if it part of the name

plus the suffix - ic if the anion ends in - ate

or the suffix -ous if the oxyanion ends in -ite

- the second word is acid

What is a structural formula?

It uses letter symbols and bonds to show relative positions of atoms

resonance structure

one of the two or more equally valid electron dot structures of a molecule or polyatomic ion

What is resonance?

When more than one valid Lewis structure can be written for a molecule or ion

What is an expanded octet?

the ability by larger atoms to take more than 8 electrons

How are electron pairs located in a molecule?

They are located in a molecule as far apart as they can be

What is the VSEPR model?

Valence Shell Electron Pair Repulsion model- model used to determine the molecular shape based on arrangements that minimize the repulsion between electron pairs

What is hybridization?

a process in which atomic orbitals mix and form new, identical hybrid orbitals

How do you determine hybridization?

You can find the hybridization of an atom by finding its steric number: The steric number \= the number of atoms bonded to the atom + the number of lone pairs the atom has. If the steric number is 4, the atom is sp3 hybridized.

If a molecule has 2 shared pairs of electrons and no lone pairs what is its shape? Its angle measure? Its hybrid orbitals?

It is linear

180 degree angles

sp

If a molecule has 3 shared pairs of electrons and no lone pairs what is its shape? Its angle measure? Its hybrid orbitals?

It is trigonal planer

120 degree angles

sp^2

If a molecule has 4 shared pairs of electrons and no lone pairs what is its shape? Its angle measure? Its hybrid orbitals?

It is tetrahedral

109.5 degree angles

sp^3

If a molecule has 3 shared pairs of electrons and 1 lone pair what is its shape? Its angle measure? Its hybrid orbitals?

Trigonal pyramidal

107.3 degree angles

sp^3

If a molecule has 2 shared pairs of electrons and 2 lone pairs what is its shape? Its angle measure? Its hybrid orbitals?

Bent

104.5 degree angles

sp^3

If a molecule has 5 shared pairs of electrons and 0 lone pairs what is its shape? Its angle measure? Its hybrid orbitals?

Trigonal bipyramidal

90 and 120 degree angles

sp^3 d

If a molecule has 6 shared pairs of electrons and 0 lone pairs what is its shape? Its angle measure? Its hybrid orbitals?

Octahedral

90 degree angles

sp^3 d^2

What results in a polar covalent bond?

unequal sharing of electrons - Atoms pull on electrons in a molecule unequally

What type of bond does two of the same atom form?

A non polar bond

What is the difference between polar bonds and polar molecules?

A polar bond is one where the charge distribution between the two atoms in the bond is unequal. A polar molecule is one where the charge distribution around the molecule is not symmetric.

Which substances are polar molecules and ionic substances soluble in?

Polar substances

Which substances are non-polar molecules soluble in?

Non-polar substances