CH 4 Periodic Table

4-1 How are Elements Organized

Objectives: A. Describe historical development of table

Newland’s table- arranged elements according to properties and atomic mass

Mendeleev’s table-first periodic table-elements according to properties and mass-place elements in rows with similar chemical & physical properties but left gaps for undiscovered elements in the rows

Moseley’s table-arranged elements according to properties and atomic number

B. Describe the organization of the modern table

Group- vertical columns (same number of valence electrons)

Period- horizontal rows (same number of levels)

4-2 Periodic Table

Objectives: A. Locate the families of the periodic table-describe their characteristic properties and relate to electron configuration

Main Group Elements (groups 1-2 & 13-18)

Group 1 Alkali Metals- one valence electron- s1 electron config.-most reactive metals- soft metals- lose 1 electron thus form +1 ions- react w/ metals to make alkaline (base) solutions

Group 2 Alkaline Earth Metals-two valence electrons-s2 electron configuration- very reactive metals-loses 2 electrons thus form +2 ions

Group 17 Halogens (salt maker)- seven valence electrons- s2 p5 electron configuration- most reactive nonmetals- gain 1 electron thus form -1 ions-react w/ metals to form salts- all halogens are diatomic Cl2, I2, etc

Group 18 Noble Gases-eight valence electrons and satisfy the octet rule and thus very stable (un-reactive)-s2 p6 electron configuration

Hydrogen (class by itself)-can lose or gain 1 electron

B. Locate metals

Transition metals groups 3-12-may lose different number of electrons to become stable thus form multiple + ions-not as reactive as group 1 or 2- fill d sublevels

Properties- lose electrons to become stable thus form + ions-conduct electricity and heat-some are ductile (pulled into wire) and malleable (hammered into thin sheets)

Lanthanides – fill 4f sublevels-as reactive as group 2

Actinides-fill 5f sublevels-radioactive

Alloys-mixture of two or more metals (stainless steel/brass/sterling silver)

4-3 Trends in the Table- trends in properties

Objectives: A. Describe trends in ionization energy and relate to atomic structure

Ionization energy-energy needed to remove a valence electron

Element + ionization nrg → Element+ + electron

Trends- ↓ decrease (valence e- are farther from nucleus and nucleus becomes shielded by more inner e-) and → increase (nuclear charge increases)

B. Describe trends in atomic radius energy and relate to atomic

structureatomic radius (size of atom) bond radius (half the distance between two bonded atoms)

Trends- ↓ increase (addition of more energy levels as you move down a group and shielding of nucleus) and → decrease (nuclear charge increases and pulls the electron cloud closer to nucleus)

C. Describe trends in electronegativity and relate to atomic structure

electronegativity- the ability of an atom to pull the valence electrons from the atom it is bonded to (tug of war) (the nucleus is what is pulling the valence electrons)- Fluorine has the highest electronegativity value 4.0

Trends- ↓ decrease (shielding of the nucleus thus less pull) and

→ increases(nuclear charge increases thus has a greater pulling affect) until you get to the noble gases they decrease

D. Describe trends in ionic size, electron affinity, melting and boiling point and relate to atomic structure

Ionic size- Trends-↓ increaseand → cations (+) decrease and

anions (-) increase

Electron affinity- a measure of an atoms ability to gain a electron while not in a bond Trends- ↓ decrease(shielding affect) and → increase (nuclear charge increases)

Melting point & boiling points- They gradually increase until the middle of the d block and decrease as you move toward p, then gradually increase again in the middle of the p block and then decreases.

4-4 Where did the elements come from

Objectives: A. Describe how naturally occurring elements form1-93 found in nature-found in living organisms mostly C-H-O-N-P-S

B. Explain how transmutation changes one element into another

Transmutation- changing an element into another element through a nuclear reaction (alpha particles hitting a nucleus)

C. Describe how particle acceleration are used to create synthetic elements (alpha particles bombarding a nucleus)-cyclotron (particle accelerator) particles fuse w/ nucleus to create heavier atoms- synchrotron- once these superheavy elements are made they decay into lighter elements