Periodic Table R08

The Periodic Table Elements & Families of Elements

Unit Outcomes
Number the periods (electron shells)
Number the groups (valence number)
Draw the line that separates the metals from the nonmetals
Write the oxidation numbers
Identify atoms that are solid, liquid and gases at room temperature

Unit outcomes, continued
Learn names and symbols of the elements shown below.

Unit Outcomes, continued
Identify trends across the periodic table
Identify key properties of metals and nonmetals
Locate the families
Alkali metals, Alkaline earth metals, transition metals, metalloids, Halogens, Noble gases
Identify key properties of families
Learn key vocabulary—solid, liquid, gas, ‘full’, reactive, conductor, brittle, melting point, etc.

Periodic Table

Elements Defined
Elements are substances that cannot be broken down into simpler substances by ‘ordinary’ chemical means such as by heat, light, electricity, or reaction with other substances
special equipment, such as a particle accelerator, or temperatures like those inside the sun can break down elements

Periods and Groups

Periods
Horizontal Rows are called PERIODS
Period number = # of electron shells of atoms in each row
Period 1 atoms all have 1 electron shell
Period 2 atoms all have 2 electron shells
… etc.
Period 7 atoms all have 7 electron shells

Groups
Vertical Columns are called GROUPS
Group number = # of electrons in the outermost shell of atoms in each column
Group 1 atoms have 1 electron in their outermost shell
Group 2 atoms have 2 electrons in their outermost shells
… etc.
Group 8 atoms all have ‘ full ’ outermost shells
e.g., Helium has 2 e- in outermost shell
e.g., Neon and argon have 8 e- in the outermost shell

Group Number/Valence Electrons
Group number = number of valence electrons
Valence electrons —electrons in the outermost shell
determine how an atom combines with other atoms
its chemical properties
Group numbers can be written with Arabic (1, 2, 3, etc.) or Roman numerals (I, II, III, etc.)
Use Roman numerals to avoid confusion

Ions
ION (definition) — an atom (or group of atoms) that is positively or negatively charged; a charged particle
Na +1 Na ---> Na + + 1e-
Be ? Atom + ion donates an e-
B 11 p+ 11 p+
N 11 e- 10 e-
O
F Cl + 1e- --- > Cl-
Atom accepts an e- - ion
17 p+ 17 p+
17 e- 18 e-

Electropositivity
the ability of an atom to lose electrons and form positive ions.
http://www.meta-synthesis.com/webbook/35_pt/pt.html

Electronegativity
the ability of an atom to gain electrons and form negative ions
the stronger an atom pulls electrons, the higher its electronegativity

Oxidation Numbers
The number of electrons donated (lost) or accepted (gained) by an atom
Donate 1 to 4 electrons
Oxidation # +1, +2, +3, +4
Form positive ions (+1 ion, +2 ion, +3 ion, etc.)
Accept 1 to 4 electrons
Oxidation # -4, -3, -2, -1 (-1 ion, -2 ion, -3 ion, etc.)
Form negative ions
Do not donate/accept electrons
Oxidation # 0
Atoms become stable (get ‘full’ outer shells) by donating or accepting valence electrons!

Oxidation Numbers

The Elements (1955)—A Song
Read the ‘lyrics’ as the song plays.
Pay attention to the pronunciation of the elements.
Can you sing along? Give it a try!
animation
by Tom Lehrer, Maths professor at Harvard

Solids, Liquids, Gases

Solids, Liquids, Gases
Liquids :
Br, Hg
Gases :
H, N, O, F, Cl, He, Ne, Ar, Kr, Xe, Rn
Solids :
All other elements

Elements
Synthetic (man-made)
Atomic numbers 43, 61, 93-118
Naturally occurring (found in nature)
All other elements

Metals (  ) and Nonmetals (  )

Metals and NonMetals
Different electron cloud configurations of elements create (result in) different properties
Metals: outer shells with few electrons
Tend to lose electrons, form positively charged ions, in chemical reactions
Nonmetals: outer shells are nearly full
Tend to gain electrons, form negatively charged ions, in chemical reactions , OR share electrons and form a covalent bond

Metals VS Nonmetals
Metals
good conductors of heat & electricity
ductile
can be drawn out into wires
malleable (bendable)
can be forced (hammered) into different shapes
high melting points so solid at room temperature
form positive ions, cations
form basic oxides
Nonmetals
Good electrical insulators; nonconductors of electricity
brittle & crumbly in solid form
relatively low boiling points
form negative ions, anions
form acidic oxides

Acids and Bases

Metals and Nonmetals
Metals
react with nonmetals to form compounds
Nonmetals (Group 7)
very reactive
form ionic bonds with metals
form covalent bonds with other nonmetals

Trends: Metallic Properties

Metalloids and Diatomics
7 metalloids
B, Si, Ge, As, Sb, Te, Po
Intermediate (in between) physical and chemical properties (metals and nonmetals)
silicon and germanium, are semi-conductors (computers)
7 diatomics
H, N, O, F, Cl, Br, I
H 2 , N 2 , O 2 , F 2 , Cl 2 , Br 2 , I 2

Trends across the Periodic Table
as you move down a group (  )
Atomic number, mass, density and size ( radius ) increases
Melting points decrease ( metals )/ increase ( nonmetals )
Reactivity increases ( metals )/ decreases ( nonmetals )
*Fr and F are 2 most reactive elements*

Trends across the Periodic Table
as you move across a period (  )
Atomic number and mass increases
Size (radius) decreases
Hardness and melting points increase ( metals )
Reactivity decreases ( metals )/ increases ( nonmetals )

Atomic Number and Mass

Size (atomic radii)
“ Atoms with more
electrons will be bigger.”
top to bottom
X left to right
Why?
Protons (+)
AND
electron shells (-)

Summary of P.T. Trends Metal Atoms: relatively large atoms with weak attraction for electrons more metallic Nonmetal Atoms: relatively small atoms with strong attraction for electrons more nonmetallic

Mendeleev’s Periodic Table (1869)
Increasing atomic weight/mass
Repeating chemical properties/reactivity in rows
Left empty spaces…why?
Big Difference?

Other Possibilities?

Galaxies

Spirals

Which is your favorite?
Check out this website:
http://www.meta-synthesis.com/webbook/35_pt/pt.html

Families

Families
Definition: groups of elements that have similar chemical properties
Chemical properties: valence number, reactivity (with water, a base, an acid), behavior in solvents, radioactivity
Physical properties: state, color, m.p. and b.p., hardness, malleablility, density, conductivity, etc.
Examples of Families
Alkali Metals, Alkaline Earth Metals, Transition Metals, Halogens, the Noble Gases
Found in columns and/or series (rows)

The Top and the Middle

Hydrogen, Helium and Transition Metals
Hydrogen —properties of both group I and VII
sometimes missing an electron +1; sometimes with an extra electron -1; doesn’t belong to any family
Helium —placed in group VIII
yet unlike all other elements, it can only have two electrons in its outer shell
Transition Metals —in center section
have special electron rules
+2 (unless otherwise noted)
Cu I, Cu IV, etc.

Alkali Metals (Li, Na, K, Rb, Cs, Fr)
Most reactive family of metals
Group I: only 1 e- in outer shell
More reactive as move down the group, as size increases
Never found free in nature
Kept under oil in lab
Metals ( but not always typical metals* )
Good conductors of heat/electricity
Malleable and ductile
All soft (can be cut with a knife) and shiny and lighter (less dense) than other metals (float on water)*
Solid at room temperature*
M.P and B. P are positive/lower than most metals

Alkali Metals
Form ionic compounds ( +1 positive ion, cation )
Compounds formed are white metallic solids
Dissolve in water --> colourless solutions
Sodium chloride (NaCl) table salt
Very reactive with water ( and chlorine and oxygen )
React with water to form bases (alkaline solutions) … ‘Alkali’ metals
Sodium and potassium ions are important parts of body fluids (electrolytes)
Rb, Cs and Fr are dangerous (Fr is radioactive)

Alkali Earth Metals (Be, Mg, Ca, Sr, Ba, Ra)
2nd most reactive family of metals
Group II: 2 e- in outer shell
Lose valence electrons and form positive ions, +2 charge
Never found free in nature
Metals
Similar properties to alkali metals
Electrical conductors; malleable and ductile
Silvery but harder and more dense, w/ higher M.P and B.P
Form ionic compounds, react with water to form alkaline suspensions
Na and K, and Ca and Mg ions are important in our bodies

Transition Metals
21 (Scandium) through 29 (Copper)
39 (Yttrium) through 47 (Silver)
57 (Lanthanum) through 79 (Gold)
89 (Actinium)
and all higher numbers

Transition Metals
able to put more than 8 e-
(up to 32 electrons) in the shell that is one in from the outermost shell
gold (Au) 2-8-18-32-18-1
can use the two outermost shells to bond with other elements
allows them to bond with many elements in a variety of shapes
range of oxidation states

Transition Metals
Very good conductors of heat/electricity
Malleable and ductile
Hard, tough, strong
High M.P. and density
Low reactivity (compared to Group I and II Metals)
Most form brightly colored compounds
Uses: building structures, electric cables, radiators, colored paints, catalysts for industrial reactions, etc.

The Halogen Family (F, Cl, Br, I, At)
Group XVII: 7 e- in their outer shell
Very reactive—with many different elements (especially Group I and II metals)
Form both ionic and covalent compounds (-1 anion)
Never found free in nature; always in compounds
Nonmetals See: diatomics
Electrical insulators
Crumbly and brittle (solid)
Characteristic colors and odors
M.P. and B. P. are low
solid (I 2 ), liquid (Br 2 ) or gaseous (F 2 , Cl 2 ) at R.T.
Can be poisonous
Used in bleaches, insecticides, dry cleaning, toothpaste

The Noble Gases (He, Ne, Ar, Kr, Xe, Rn)
Group VIII: All have full outer shells (2 e- for Helium, 8 e- for all others)
Unreactive, ‘stable’ or ‘inert’ (no need to react!)
Always found free in nature; monatomic
Nonmetals
Colorless gases at R.T. (Earth’s atmosphere)
Low B.P.
Uses: advertising signs and fluorescent lighting (neon), light bulbs (argon), car headlights (xenon), balloons and airships (helium), lasers (krypton)

Periodic Table R08

by Karen Reau on Oct 19, 2009

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Periodic Table R08 — Presentation Transcript