chemical bonds, molecules, and ionic compounds

what are compounds

a substance formed when two or more different chemical elements are chemically bonded together in a fixed ratio

-ex. H2O, NaCI+, CH4

what are the 2 basic types of compounds

-molecular compounds

-ionic compounds

molecular compounds

when atoms share electrons through covalent bonds

covalent bonds

bonds made by sharing electrons

-results in the formation of molecules

sharing of valence electrons

can be shared unequally or equally

-covalent bonds can exist as single double or triple bonds

non - polar covalent bonds

equal sharing of electrons

polar-covalent bonds

unequal sharing of electrons between atoms

-forms when an electronegative element is present in a molecule

what is an electronegative element

an element that attracts electrons to itself, it leads to unequal sharing of e-

ex. hydrogen & nitrogen

partial charge

exist between polar covalent bonds

-happens because one side is partially negative and the other partially positive

partiality positive

That atom has fewer electrons nearby most of the time, so it’s slightly positive

partially negative

That atom has electrons closer to it most of the time, so it’s slightly negative compared to the rest of the molecule.

what is the net charge of a polar covalent bond

net charge is still neutral because it is not actually gaining or losing electrons, they are just being shared

polar molecules

-have polar covalent bonds

-hydrophillic

-water soluble

-has an electronegative atom

non polar molecules

-have non polar covalent bonds

-hydrophobic

-water insoluble

atoms with what #’s of valence electrons will share electrons/form covalent bonds, to become stable

4,5,6

atoms with what #’s of valance electrons will lose or gain electrons/form ionic bonds, to become stable

1,2,3,7

what is an ionic compound

product of an ionic bond

-not nuetral

what happens in an ionic bonds

when one atom gives electrons to another atom so both their valance shells are stable

cation

atom that donates an electron; becomes partially charged (gained aura)

anion

electron that receives an electron; becomes negatively charged (its in debt)

ionic bonds and charges

bonds made by charge attractions, cation is attracted to anion

-one atom gives an electron to another so they both have filled valence shells

-ex. Na+CI-

ionic compounds and water

ionic compounds disassociate in water

what happens to when an ionic compound mixes with water

-negative side of water is attracted to the cation (+), positive side of water is attracted to anion (-)

-this causes the water to form hydration spheres around ions keeping them sperated

hydrogen bonds

A hydrogen bond is a weak “magnet-like” attraction between molecules.

• One molecule has a hydrogen that’s a little positive.

• Another molecule has something like oxygen or nitrogen that’s a little negative.

• They stick together weakly — like Velcro.

what do hydrogen bonds form between

-water molecules (H&O atoms)

-amino acids

how are hydrogen bonds related to DNA

bases of dna are bonded using hydrogen bonds