Glossary of Chapter 0 and Chapter 1 - Atomic Structure

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1L equals how many cm^3?
1000 cm^3
Density is measured in what?
g / cm^3 or mass / volume
Formula for volume?
mass / density
Molecular formula
gives identities and numbers of atoms in a molecule
Avagadro’s number
6.02 x 10^23, 1mole = 6.02 x 10^23 atoms
# of moles ?
mass in grams / mw
empirical formula?
smallest whole #’s that give the same ratio of atoms in a molecule (to reduce molec. Formula divide all subscripts by greatest common factor)
Percentage composition by mass?
take the empirical formula molecular weight and compare individual molecule to mw.
How do you find the empirical formula from % composition?
-start with 100g of substance

-find the # of moles (g of substance over molec. Weight)

-find the ratio of the number of atoms
How do you find the limiting reagent?
convert grams to moles and look at stochiometric coefficients
What is the oxidation state of an atom?
the charge it would have if the compound were ionic
What are the rules for assigning oxidation states?
*The highest rule takes precedence

1 group 1 metals have oxidation states of +1 and group 2 of +2
2)Flourine has a -1 oxidation state

3)Hydrogen has a +1 oxidation state

4)Oxygen has a -2 oxidation state
5)Halogens have a -1 oxidation state

6)Group 16 atoms (oxygen family) have -2 oxidation state
What is the atomic # ?
Z; the number of protons,
What is a nucleon?
central nucleus which contains protons and neutrons known collectively as nucleons
What is the atomic mass or mass #?
Atomic mass = protons + neutrons

A = Z + N
What is an isotope?
same atomic # but differ in mass number do to the difference in neutrons
What is an ion?
a neutral atom that gains or looses electrons and becomes charged.
What is the shell number, n ?
-size and energy of the orbital

-the greater the n value the greater the electron's energy and avg. distance from the nucleus

-can be any whole # starting with 1
What is the subshell number,l ?
the shape of the orbital:

l = 0 -> s subshell (groups 1,2)

l= 1 -> p subshell (B - He)

l= 2 -> d subshell (Sc - Zn)

l=3 -> f subshell (bottom 2 periods)

- l can be 0,1,2 .. n-1
What is the orbital # m sub l ?
describes 3-D orientation of orbital

-ex. if l = 2 m sub l can be -2, -1, 0, 1, 2
What is the spin #, m sub s ?
-spin of electon in orbital

-can either be +1/2 or -1/2(spin down)
Electron configuration rule #1?
electrons occupy the lowest orbitals available

-electron subshells are filled in order of increasing energy
Electron configuration rule 2?
Hunds rule: electrons in same subshell occupy available orbitals singly before pairing up
Electron configuration rule #3?
no 2 electrons in same atom can have the same set of 4 quantum #'s
How do you write an element in the d block?
when in the d block subtract 1 from the period number

ex. Sc; is in period 4 so you subtract 1 from the period # and say that it puts its valence electrons in the 3d subshell : [Ar] 4s2 3d1
Exceptions to the rule
Cr-> [Ar]4s1 3d5--bc atom obtains more stable, lower energy state by promoting 1 of its e's to 3d to give half filled subshell

-same concept for Mo

-Cu, Ag, and Au donate electron from s subshell to give complete d subshell
What electrons are removed (ionized) in transition metals?
the valence s electrons are always lost first; only after these are all gone do any d electrons get ionized

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