MIDTERM STUDY (unit 4/5 Flashcards
Only s and p orbitals are
Valence electrons
Valence electrons:
e- in outer most energy level
s sublevel:
2 e- and Sphere shape
p sublevel:
6 e- and dumbbell shape
Principles that govern electron configuration:
- Pauli Exclusion Principle
- Hund’s Rule
- Aufbau Principle
Pauli Exclusion Principle:
2 e- in same orbital must have opp spins
Hunds Rule:
e- in same sublevels occupy empty orbitals before they pair up
Aufbau principle:
e- occupy positions of lowest energy level first
Orbital Notation:
shows all e- in energy level order, with e- pairing, and opp spins
Lewis Dot Notation:
shows only valence e-
Bohr Model Diagram:
shows all e- per energy level (does not delineate between sublevels)
Electron Configuration:
use of superscripts to show the # of electrons per sublevel
Nobel Gas Configuration:
use of Nobal Gas from the period above, then show configuration of e- after that noble gas
Isoelectronic:
atoms of two different elements with the same # of e-
Dimitri Mendeleev:
developed periodic table of known elements and arranged them in order of increasing atomic mass and later ordered according to chemical properties
What did Mendeleev predict about the empty spaces in his periodic table:
they were undiscovered elements
What was the problem with Mendeleev’s new periodic table:
When elements were arranged according to similar properties, some had to be placed out of order of atomic mass
Henry Moseley:
ordered elements by atomic number (# of p+)
Periodic Law:
states that the physical and chemical properties of elements are periodic functions of their atomic #’s
Periodic groups;
(18) Elements of the same group have same valence configuration, valence electrons, and similar chemical properties
Periodic Periods:
(7) elements of same period have the sma e# of occupied energy levels
The number of valence electrons in MAIN GROUP ELEMENTS is = to
its group # or group number minus 10
What are the three classes of elements:
Metals, Nonmetals, Metalloids
How are elements arranged:
in order of increasing atomic # (# of protons) NOT MASS
Properties of metals:
-easily oxidized (lose e-)
- good electrical conductors
-shiny, malleable, ductile
- low ionization energies
-low electronegativities
Properties of Nonmetals:
-gain e- (are reduced)
-not conductors
- dull,brittle
-high ionization energies
- high electronegativity
(4 types) Metals:
Alkali Metals
Alkaline Earth Metals
Transition Metals
Inner transition metals
(2 types) NonMetals:
Halogens
Noble Gases
Alkali Metals:
have 1 valence e-
NEVER found in pure form bc too reactive
Reactivity increases down group
Most reactive group of metals
soft and silvery in color
Alkaline Earth Metals:
have 2 valence e-
less reactive
not found in pure form
“Basic”
Transition Metals:
d/block elements
Inner Transition Metals:
lanthanides and actinides
(3 things) Halogens:
have 7 valence e-
most reactive group of NONMETALS
ONLY found in pure form as diatomic element
(4 things ) Noble Gases:
8 valence e-
chemically unreactive
only found in pure form in nature
colorless and odorless
Atomic Radius:
Left to right # of energy levels stay the same and # of protons increases in nucleus so it increases the positive nuclear charge - pulls the electrons in closer
Atomic Radii:
one half the distance between the nuclei of identical atoms that are bonded together
Ionization energy def:
energy required to remove one electron from an atom
Ionization energy:
-As atomic radius decreases across the period, valence e- being removed is closer to positive nucleus so harder to remove and need more energy
Electronegativity def:
a measure of the ability of an atom in a chemical compound to attract e- from another atom
Electronegativity:
as atomic radius decreases across period, the positive nuclear charge increases making the atom’s ability to “pull in” e- much greater
Ionic Radius:
Metals- decreases
nonmetals- increases
Metals:
valence e- are lost to create cations
Nonmetals:
Valence e- are gained to create anions
Period Trends:
(across the period) affected by increasing nuclear charge, an increasing number of p+ but same number of energy levels.
Group Trends:
(down the group) affected by shielding. shielding increases down the group due to increasing # of energy levels
Shielding:
inner levels of e- repel the outer (valence) e- blocking the nuclear effect on the e-
How many naturally occurring elements are there?
92
Periodic Families (groups):
Alkali metals
alkaline earth metals
transition metals
Halogens
Noble Gases
Lanthanides (inner transition metals)
Actinides ( inner transition metals)
