Download PT trends

BETWEEN YOU AND A PARTNER, GRAB ONE
TEXTBOOK…
Turn to p. 193 (Organize Elements minilab)
 Cut a piece of construction paper into 10
squares and write the information for each
element on each separate sheet
 Follow the instructions and answer the
questions on a separate sheet (one sheet per
pair)

FOR QUIZ B
Chapter 6
PERIODIC TABLE
DEVELOPMENT OF THE PERIODIC TABLE

J.W. Dobereiner
 Early
 This
1800’s, classify elements in sets of 3
Element
Mass
Li
7
Na
23
K
39
trend didn’t work for most of the elements known at
the time
JOHN NEWLANDS


1865 – noticed trend that every 8th element had same
properties (law of octaves)
Unfortunately, this didn’t work for all the known
elements at the time, and it was dismissed
MENDELEEV

Considered the father of the modern
Periodic table
arranged by increasing
atomic mass (1869)
MOSELEY
Discovered that the # of protons = atomic
number
Developed concept of arranging PT by atomic
number
Periodic law – there is a periodic repetition of
properties when elements are arranged by
atomic #

Periods vs. groups/families

Metals vs. nonmetals vs. metalloids
 What
are some properties?
 Are all nonmetals gases?

Representative elements vs. transition
metals vs. inner transition metals
What do all elements in the same group
have in common?
Valence electrons
All elements in the same group exhibit
similar characteristics
Sodium and Potassium are both highly
reactive in water
So, what subatomic particle is
responsible for determining properties of
an element?
How many valence electrons?
Alkali metals:
1 valence electron, s block
Alkaline earth metals:
2 valence electrons, s block
Halogens:
7 valence electrons, s and p block
Noble gases:
8 valence, totally filled s and p block, except for which
element?
Helium – his s block is filled with only 2
Transition metals: (Groups 3B – 12B)
2 s-block electrons, and various d block electrons
Called transition metals b/c electrons can move
around the d block
Inner transition metals:
2 s-block electrons and various f block electrons
Representative elements: (Groups 1A – 8A)
any of the s or p-block elements
SHIELDING

SHIELDING
Which atom has more
shielding?

We’ll be coming back to
this idea of shielding often
ATOMIC RADIUS
Half the distance between the nuclei of 2
like atoms
 No definite edge of electron cloud

atomic
radius
TRENDS IN ATOMIC RADIUS

Down the Groups




What is changing about the
atom as we go down?
# of shells = energy level
More shells = bigger atom
Across the Periods


Same period means same #
of shells
What is changing as we go
across a period?
Be
Li
Na
K
Rb
C
F
 Who
is larger?
Mg
or S?
Br or K?
C or Sn?
 Who
is smaller?
Li
or N?
F or I?
 Put
the following elements in order of
increasing atomic radius
Ca, Fe, Br, O, Ba
WHAT IS AN ION?

An ion is an atom with a charge (+ or -)

In a sodium atom, how many protons and
electrons do we have? How many valence e-?
 11
p+ and 11 e 1 valence e
Can we lose protons?
 No,
that would change the element
OCTET RULE

An atom is most stable when it has a full
outer shell
 How
many valence electrons = full?

An atom will lose or gain electrons to achieve
this – whichever is easiest

Sodium has 1 valence electron. Do you
think he loses or gains?
 Loses,
then there will be 1 more proton than
electrons
 If
an atom has 2 valence e-, what will it
do?
 What group is this? What charge?
 What
charge does aluminum form? Lose
or gain?
 +3,
loses 3 electrons
If an ion is positive it has ______ eIf an ion is negative it has ______ e-
SIZE OF IONS (IONIC RADIUS)
Na
Na+
e-
F
e-
F-
 Who
is larger?
Mg
or Mg2+?
S or S2-?
O2- or F1-?
First,
determine if you have lost or gained
electrons… Which particle do you have
more of (who has the power?)
IONIZATION ENERGY

IE is the energy required to remove an electron
from an atom (and make it an ION)
KEEP SHIELDING IN MIND
Babysitter analogy
A couple First Ionization Energies:
Li = 520 kJ/mol
O = 1310 kJ/mol
Who is harder to take an electron from?

Which has the higher ionization energy?
Li or N?
Cs or Li?
O or S?

Which has the lower ionization energy?
 K or Fe?
 F or Br?
TURN IN PROJECTS UP FRONT…
Warm up:
As we go down the groups on the PT, the size of
the atom __________, making it __________ to
take an electron away, making the ionization
energy __________
As we go left to right across a period, the size of
the atom _________, making the ionization
energy __________.


Arrange in decreasing ionization energies:
Cr, Br, I, Li, N
ELECTRONEGATIVITY (EN)

How well an element can attract electrons from
another element in a bond
 Atoms
fill their outer shells when they bond with
another atom

How might EN relate to IE?
 If
it’s hard to take an electron away, what kind of
attraction do you think it has?

What do you think the electronegativity of a
noble gas might be? Do they want to bond?
 Zero

Arrange in order of increasing electronegativity:
Mg, F, Ne, Cs, Al
NOW THE EASY WAY…
& OVER
IE and EN increase
RaDius Decreases
UP
But it is good to understand the WHY so you can
double check yourself…
 Put
in order of decreasing atomic radius:
Ca, Al, Ne, Rb, Br, Au, Zn, C
What order is this for ionization energy?
(increasing or decreasing)
 Skip
#8
 Add
this question (doesn’t matter where):
Determine the larger radius in the following:
(what are the the
a. Mg or Mg2+
things with charges
b. Cl or Cl1called, and how do
c. Cl1- or P3they get those charges?)
CONTINUE FROM YESTERDAY…
Between you and a partner, grab a textbook:
 Turn to p. 193 (Organize Elements minilab)
 Cut a piece of construction paper into 10
squares and write the information for each
element on each separate sheet
 Follow the instructions and answer the questions
on a separate sheet (one sheet per pair)

When finished, turn it in and grab a BINGO card