lesson 6 the periodic table anything in black letters = write it in your notes (‘knowts’)
TRANSCRIPT
Lesson 6Lesson 6
The Periodic TableThe Periodic Table
Anything in black letters = write it in your notes (‘knowts’)
Objectives for Lesson 6
1. Describe ways in which the modern periodic table is organized
2. Understand electron configuration patterns in the periodic table
3. Describe and explain trends in the periodic table
Section 1 – Organizing the Elements
Section 2 – Periodic Trends
Section 1 – Organizing the ElementsSection 1 – Organizing the Elements
Dmitri Mendeleev (1869) – created 1st modern periodic table.
Mendeleev arranged elements with similar properties.
He also left gaps where proposed elements should be.
These gaps were later filled in as more elements were discovered.
Ga & Ge Discovered later
Similar properties
Mendeleev’s table was an accepted success because it predicted the properties of elements that had not yet been discovered.
Woo Hoo!
Today’s periodic table is arranged in order of increasing atomic number (not mass).
Also, elements with similar chemical properties are placed in the same vertical column.
Columns are called groups or families.
Horizontal rows are called periods.
Valence Electrons – Electrons in the highest occupied energy level; maximum of 8.
Elements in the same column have similar properties because they have the same number of valence electrons.
Electrons in the s and p orbitals of the outer shell are the valence electrons.
8 is the maximum number of valence electrons
Atoms tend to gain or lose electrons to have 8 e-
Sodium: 1s22s22p63s1
Magnesium: 1s22s22p63s2
Fluorine: 1s22s22p5
Nitrogen: 1s22s22p3
The Octet Rule –
The noble gases are chemically stable because they have a full outer energy level (valence).
Atoms tend to gain or lose electrons to have 8 e-
Sodium: 1s22s22p63s1
Magnesium: 1s22s22p63s2
Fluorine: 1s22s22p5
Nitrogen: 1s22s22p3
Electron configurations for Group 1
(valence e- underlined)1s1
1s22s1
1s22s22p63s1
1s22s22p63s23p64s1
1s22s22p63s23p64s23d104p65s1
[Xe]6s1
[Rn]7s1
1s22s22p5
1s22s22p63s23p5
Get the idea?...
Why is it called the Periodic Table of the Elements?
The properties of the elements repeat going across each row.
Three broad classes of elements; metals, metalloids, nonmetals
Metals – good conductors of heat and electricity, shiny, most are solid at room temp (except Hg), malleable, ductile
Nonmetals – not metals!, most are gases at room temp
Metalloids – can show properties of both metals and nonmetals
Practice1.Explain why Mendeleev’s table was an accepted success.
2.Why is the table of elements called the “periodic” table of elements?
3.State 4 properties of metals.
4.Explain the reason that elements in the same column have similar chemical properties?
5.How can you tell if an elements is a metal, nonmetal or metalloid from the periodic table?
6. Name an element that is part of the
a) Halogen family
b) Alkali metal family
c) Alkaline earth metal family
d) Transition metals
e) Inner transition metals
f) Noble gas family
7. A horizontal row in the periodic table is called a _____.
8. Write the electron configuration for
a) Nitrogen
b) Chlorine
c) Rubidium
9. How many valence electrons are in each element from question 8?
Atomic size
Ionic size (skip!)
Ionization Energy
Electronegativity
Section 2 – Periodic TrendsSection 2 – Periodic Trends
Atomic SizeA
tom
ic r
adiu
s (p
m)
Atomic number
Atomic size generally decreases from left to right across a period.
As Z increases across a row, the +/- electrical attraction increases, making the atom smaller.
As Z increases down a group, another energy level is added to the atom which ‘shield’ the outer electrons from this nuclear attraction.
Ion – atom or group of atoms that has a positive or negative charge.
Ions are formed when electrons are transferred between atoms.
Cation – ion with a positive charge.
Anion – ion with a negative charge.
Metals tend to form cations
Nonmetals tend to form anions
Ionization Energy – energy required to remove an electron from an atom.
lithium atom
lithium ion
1st ionization energy = 520 kJ/mol
Lithium +2 ion
2nd ionization energy = 7297 kJ/mol
lithium +1 ion
Ionization Energy – energy required to remove an electron from an atom.
lithium atom
lithium ion
1st ionization energy = 520 kJ/mol
Lithium +2 ion
2nd ionization energy = 7297 kJ/mol
lithium +1 ion
Ionization Energies of Some Common Elements
Symbol First Second Third
H 1312
He (noble gas) 2372 5247
Li 520 7297 11,810
Be 899 1757 14,840
C 1086 2352 4619
O 1314 3391 5301
F 1681 3375 6045
Ne (noble gas) 2080 3963 6276
Na 496 4565 6912
Mg 738 1450 7732
S 999 2260 3380
Ar (noble gas 1520 2665 3947
K 419 3096 4600
Ca 590 1146 4941
Fir
st io
niz
atio
n e
ner
gy
(kJ/
mo
l)
Atomic number
1. What does 1st ionization energy mean?
2. Explain why the 2nd ionization energy of Li and Na is so much higher than the 1st ionization energy.
3. Explain why the 1st ionization energy of Na is smaller than Li.
4. Why are the ionization energies of the noble gases so large?
Electronegativity – tendency of an atom to attract electrons of another atom.
Metals have low e-neg values,
Nonmetals have high e-neg values
B<H<C
Noble gases do not have e-neg values
Electronegativity Values for Selected Elements
H 2.1
Li 1.0
Be1.5
B2.0
C2.5
N3.0
O3.5
F4.0
Na 0.9
Mg1.2
Al1.5
Si1.8
P2.1
S2.5
Cl3.0
K 0.8
Ca1.0
Ga1.6
Ge1.8
As2.0
Se2.4
Br2.8
Rb 0.8
Sr1.0
In1.7
Sn1.8
Sb1.9
Te2.1
I2.5
Cs 0.7
Ba0.9
Tl1.8
Pb1.9
Bi1.9
Lesson 6 Practice1.How does the size of an atom change from left to right a) across a period? b) down a column?
2.Give the explanation for question 1.
3.What is an ion and how are they formed?
4.Metals tend to form _____ ions and nonmetals tend to form _____ ions.
5.Define Ionization Energy.
6.Describe the trend in ionization energy in the periodic table.
7. Define electronegativity.
8. Which atom is the a) most electronegative, b) least electronegative?
9. Which atom has the highest ionization energy?
10. How do electronegativity values differ between metals and nonmetals?
A little more for Chapter 6…
Lesson 6 Quiz ReviewTerms to know:
valence electron,
cation,
anion,
electronegativity,
ionization energy (1st & 2nd)
Things to know:
Metal, nonmetals, metalloids locations
4 properties of metals
metals form cations, nonmetals form anions
family names (alkali, alkaline earth, noble, halogens, transition and inner transition)
electronegativity and ionization energy trends
electron configurations (w/out aufbau diagram)
Possible Short Answer Questions:
1. Why was Mendeleev’s table an accepted success?
2. Why is the periodic table called the “periodic” table?
3. What causes elements in the same column to have similar chemical properties?
4. What is an ion and how are ions formed?
5. Why is the 2nd ionization energy of Na so much larger than the 1st ionization energy?
Energy levels can also be called electron shells