Chemistry Final 10th

Valence Electrons

Electrons in the outermost shell of an atom

Octet Rule

When bonding with other atoms, atoms will gain or lose electrons (whichever requires less energy) in order to fill the outermost energy level with 8 electrons

Why are noble gasses noble?

because they already satisfy the octet rule and are stable

What elements are an exception to the octet rule?

helium, it only needs 2 valence electrons, beryllium, it only needs 4 electrons, and boron with only 6

Ions

atoms with a positive or negative charge due to a change in the number of valence electrons.

Cation

Positive on formed when an atom loses valence electrons

Anion

Negative ion formed when an atom gains valence electrons

What are main group elements

What are transition metals?

Ionic Bonding

a form of chemical bonding in which electrons are transferred between atoms

What does ionic bonding cause the atom to become and take on?

Ionic bonding causes atoms to become ions and take an electric charge that are opposite of one another

What does the chemical formula show

the ratio of each type of atom or ion that makes up a chemical compound

What does the element symbol indicate? (the letter assigned to every element)

the type of atoms or ions present

What does a subscript represent?

the number of that atom or ion

Polyatomic ion

ion made of two or more atoms bonded together

Lewis structure

a diagram that illustrates the valence electrons of atoms or molecules

Another name for lewis structure

electron-dot diagram

How are valence electrons represented?

with dots and dashes

a triple bond forms when two atoms share

3 pairs of electrons or 6 electrons

Covalent Bonding

form of chemical bonding in which electrons are shared between two or more atoms. This fulfills the octet rule and holds the atoms togther

molecular orbital

the space that is occupied by the shared electrons

what are covalent compounds also called?

molecular compounds because they exist as molecules

What are molecules?

group of atoms covalently bonded together

In covalent naming, what is the prefix for 1 atom?

Mono

In covalent naming, what is the prefix for 2 atom?

di

In covalent naming, what is the prefix for 3 atom?

tri

In covalent naming, what is the prefix for 4 atom?

tetra

In covalent naming, what is the prefix for 5 atom?

penta

In covalent naming, what is the prefix for 6 atom?

hexa

In covalent naming, what is the prefix for 7 atom?

hepta

In covalent naming, what is the prefix for 8 atom?

octa

In covalent naming, what is the prefix for 9 atom?

nona

In covalent naming, what is the prefix for 10 atom?

deca

full form of VSEPR

Valence shell electron pair repulsion

What is VSEPR used for?

to predict molecular shape

What is the VSEPR theory based on?

pairs of valence electron surrounding an atom repel each other

Steric number

number of bonded atoms + number of lone pairs

in VSEPR, what shape is it of the model has 0 lone pair and a steric number of 2?

Linear

in VSEPR, what shape is it of the model has 0 lone pair and a steric number of 3?

Trigonal Planar

in VSEPR, what shape is it of the model has 0 lone pair and a steric number of 4?

Tetrahedral

in VSEPR, what shape is it of the model has 0 lone pair and a steric number of 5?

Trigonal Bipyramid

in VSEPR, what shape is it of the model has 0 lone pair and a steric number of 6?

Octahedral

in VSEPR, what shape is it of the model has 1 lone pair and a steric number of 3?

Bent or Angular

in VSEPR, what shape is it of the model has 1 lone pair and a steric number of 4?

Trigonal Pyramid

in VSEPR, what shape is it of the model has 1 lone pair and a steric number of 5?

Seesaw

in VSEPR, what shape is it of the model has 1 lone pair and a steric number of 6?

Square Pyramid

in VSEPR, what shape is it of the model has 2 lone pair and a steric number of 4?

Bent or angular

in VSEPR, what shape is it of the model has 2 lone pair and a steric number of 5?

T-shape

in VSEPR, what shape is it of the model has 2 lone pair and a steric number of 6?

Square Planar

in VSEPR, what shape is it of the model has 3 lone pair and a steric number of 5?

Linear

in VSEPR, what shape is it of the model has 3 lone pair and a steric number of 6?

T shape

in VSEPR, what shape is it of the model has 4 lone pair and a steric number of 6?

Linear

Metallic Bonds

Atoms in a metallic solid contribute their outer electrons to a sea of electrons that can move freely between atoms

What do ionic compunds typically form between?

metal and non metal

What is the name of the structure that ionic compounds are arranged into?

Crystal Lattice

3 characteristics of ionic compounds

1) high melting and boiling point

2) be brittle

3) be soluble in water

Can ionic compounds conduct electricty?

only when its a liquid or dissolved in water

What happens when ionic compounds dissolve in water

They dissociate, which means the cations and anions separate

What do covalent compounds form between?

two nonmetals

What do the atoms in a covalent compound form when they are bonded together?

molecules

3 characteristics of covalent compounds

1) low melting and boiling points

2) not soluble in water (depends on their polarity)

3) malleable or brittle

do covalent compounds conduct electricty

no

what do metal atoms form?

metallic lattice

what is an alloy?

When atoms of different metals mix, such as steel or brass

2 Characteristics of metals and alloys

1) high melting and boiling points

2) be malleable and ductile

do metals and alloys conduct electricty?

yes

What happens in a metallic lattice?

outer electrons are delocalized and create a sea of electrons where metal cations are formed

What is a metallic bond?

the attraction of cations for the delocalized electrons in a metallic lattice

what is electronegativity?

atom’s ability to attract electrons, the greater it is, the greater attraction it has to attract electrons

Nonpolar covalent bond

when electrons are shared equally between two atoms in a covalent bond

What is a polar covalent bond?

when electrons are shared unequally between two atoms in a covalent bond

shared electrons are more likely to be found near the atoms with the higher ______

electronegativity

Define dipole

a molecule or part of molecule with a partial negative charge and partial positive charge, created by the unequal sharing of electrons

an atom with higher electronegativity is partially ___

negative

what is the electronegativity difference when it is a nonpolar covalent bond?

less than or equal to 0.4

what is the electronegativity difference when it is a polar covalent bond?

more than 0.4 but less than 1.7

what is the electronegativity difference when it is a ionic bond?

more than or equal to 1.7

True or false: it’s possible for a molecule to be made of polar bonds, but be nonpolar overall (and vice versa)

True

When will molecules be polar?

if there is asymmetric or unequal distribution of partial charges, resulting in a partially positive and a partially negative end of the molecule (an overall dipole). 

define solubility

ability of one substance to dissolve in another substance.

True or false: polar substances and nonpolar substances can mix!

false

Define intermolecular forces

forces of attraction between molecules

What physical properties are affected by intermolecular forces?

boiling and melting point, viscosity, surface tension, and capillary action

Weakest to strongest bonds

london dispersion forces → dipole-dipole forces → hydrogen bonding → ion-dipole

what are van der Walls forces?

Dispersion forces and dipole-dipole forces

Dispersion forces exist between all molecules, but they are the ONLY type of IMF experienced by ____ molecules. 

nonpolar

what factors affect the strength of dispersion forces in a molecule?

size and mass, and shape

What molecules are dipole dipole forces between ?

polar molecules

Hydrogen bonding is a specific type of what force?

dipole-dipole

What elements must H be bonded to form hydrogen bonding?

N, O, or F

ion-dipole forces exist between?

polar molecules and dissolves ions

what makes it possible for ionic substances to dissolve in polar solvents?

the strength of ion-dipole forces

what are polymers?

large molecules that consist of many repeating structural units, called monomers.

what is polymerization?

a process where polymers are made by bonding monomers

What are the two types of polymerization reaction?

addition and condensation

what is addition polymerization

when all atoms present in the monomer are retaines in the polymer

condensation polumerization

when monomers containing a special atom groups combine with the loss of a small by-product, usually water

what are chemical reactions?

the process by which one or more substances change into one or more new substances

what are reactants?

The substance that participates in a chemical reaction

What are products?

The substance that is formed in a chemical reaction (what it ends with)