Chapter 1: Life chemistry and atoms to molecules

What is matter?

any substance that has mass and takes up space

what is an atom?

smallest unit of matter

what do atoms consist of?

consists of equal numbers of protons (mass of +1) , neutrons (mass of +1), and electrons (no mass)

what is an isotope?

- different # of neutrons

- mass will be different between isotopes

What are ions?

- charged particles

- changing the # of electrons, changing the charge

what determines the type of bond atoms share?

the difference in EN

what results in smaller differences in EN?

covalent bonds

EX: when 2 atoms have very similar EN, they form a covalent bond

what results in larger difference in EN?

ionic bonds

EX: when 2 atoms have very different EN, they form an ionic bond

- ionic bonds involve the complete transfer of e-

which bonds can form crystal sturctures?

- ionic

- these are regular arrangements of anions and cations held together by oppositely charged ion

what happens with Nonpolar Covalent bonds?

electrons get shared EQUALLY because atoms have same EN or molecular geometry

what happens with polar covalent bonds?

electrons are NOT shared equally. The higher EN an atom has, they more pull of E- it has on that. (still shared)

polar ionic

very big transfer of electrons, results in stealing of electrons

which bonds create partial charges on molecules?

polar covalent bonds

what are polar bonds?

electrons spend more time orbiting the atom with a higher EN

what happens when the electrons go more towards the higher atom with EN?

the more EN atom will be slightly negative charged while the other atom will have a slightly positive charge.

- these are called dipoles

what are hydrogen bonds?

attractions between oppositely charged regions of polar molecules

what are van der waals interactions?

usually weak attractions between oppositely charged atoms in NP molecules

If a hydrogen atom gains an electron then

_____.

it acquires a negative charge

how do you know if a covalent bond between 2 atoms is polar or NP?

- by determining the atoms EN and subtracting the 2 or looking at molecular geometry

- EN are both 0 or the same? --> NP

Both ionic and hydrogen bonds involve attraction between opposite charges. So what's the difference between an ionic and hydrogen bond?

with an ioninc bond, it involves a complete transfer of e-. With hydrogen bonds, the bond strength is weaker and...

what are dipole-dipole interactions?

attractive forces that act between polar molecules

T/F: a polar substance and a nonpolar substance can form a hydrogen bond.

False, a hydrogen bond can only form when the hydrogen atom is involved in a polar bond