Unit 2 AP Chem (excluding the last two lessons)

bonding

chemical bond formed between atoms or ions when electrons are transferred or shared

valence electrons

electrons that can be found in their outermost shell of the atoms. They are electrons used for bonding.

electornegativity

measure of the tendency of an atom to attract a bonding pair of electrons

what does coloumbs law state 

attractive force between charged particles increases with an increase in charge and decreases with an increase in the distance

why does electornegativity decrease down a column

as there is greater distance from the nucleus because there is more electron shielding

why does electornegativity increase as you move across a periodic table

because the protons increase, leading to a stronger nucleur charge which increases attraction

ionic bonding 

a bond formed between 2 or more atoms or ions. Electornegativity difference is so great that the electornegative steals elctrons from the less electornegative

-very strong bonds 

-tends to happen between nonmetals and metals but there are exceptions 

electornegativity difference for an ionic bond to occur

greater than 1.7

covalant bonding

a bond formed between 1 atoms or ions. The lectronegativty difference is solow so the atoms share the electrons instead 

-happens between onmetals 

polar covalent 

-stronger than nonpolar covalent

-electrons are shared unequally

-electornegativtiy difference between 0.5-1.7

nonpolar covalant

-electrons are shared equally

-weaker than polar covaltn

-

metallic bonding

-weakest bond

-formed between metallic substances

• electonrs move freely between the different metallic atoms

• -described as sea of electrons throughout metal 

• -free movement gives metals mettalic properties 

• held by cations that are allowed to be delocalized and move anywhere, creating coloumbic attraction

• -this is why we cant use the periodic table column groups to predict the number of valence electrons as we don’t knwon which element are from any specific atom

single bond 

single lone electron of one elemnet shares the single lone of another

examples: H2, HCl

triple bond

When 3 lone lectrons bond with the 3 lone pairs of another elemnt 

Ex. N2

double bond

lone pair of elctrons of one element bond with the lone pair of another molecule 

Ex. O2, CO2

lattice 

lattice energy can be represented using a modification of Coloumbs law where the nergy is proprotional to the charges and inversely proportional to distance

-energy to sepreate ions is known as lattice energy

-lattice energy is defined as change in energy that occurs when has ions combine to form a solid

-all ionic bonds are polar and lattice structures 

enthalpy

energy required when breaking a bond or the energy released when a bond is formed 

also known as bond energy 

institial alloy

atoms added tot he metal that are small and fit in between metal atomsin the existing holes (interstices)

substitutional alloy

atoms have similar radii so they replace each other  

lewis structure

shows a representation fo how the atoms connect to form in a molecule

resonance structure 

one of several Lewis structures used to describe the delocalization of electrons within a molecule or polyatomic ion, where atoms remain fixed but electrons move between them, creating fractional bonds and charge

how to determine formal charge

-determine valence electrons

-substract the sum of the lone electrons and bonds connection to the atom

-to check it, sum for formal charges should add up to 0 for a molecule or add up to the charge of the polyatomic ion

how do covalnet bonds form

-at lowest energy state

-attraction between nuclei is greatest for shared electrons but repulsions between electrons and between nuclei is small

lattice sturcutre propoerties

-nonvolatile

-nonconductive unless they can be melted or dissolved into ions

-soluable in polar compounds

0insoluable in nopoplar compounds like oil