Periodic Law PERIODIC LAW states that many of

Periodic Law • PERIODIC LAW states that many of the physical and chemical properties of the elements tend to recur in a systematic manner with increasing atomic number. • Properties of elements are periodic functions of their atomic numbers.

Trends on the Periodic Table • Period - a row of elements on the periodic table. – Remember that sentences are written in rows and end with a period. • Group - a column of elements on the periodic table. – Remember that group is spelled group and groups go up and down.

Element Stability • Elements will tend to lose or gain electrons to become stable!! • Elements are stable when their outermost energy level is full(of electrons)! • Although some energy levels can hold more than 8 electrons, 8 is enough for them to think they’re full. • Eight is the “magic #” except for H and He. • Their magic # is 2!

What happens when Elements gain or lose electrons to become stable? • When atoms gain or lose electrons to become stable, they become “charged”(ions)!! How many electrons will an atom gain or lose to become stable? • The number of electrons gained or lost depends on: 1. How many valence electrons the atom has! 2. What is easiest!! • It is easiest to gain or lose the fewest!

Ex. The alkali metals have 1 valence electron. Is it easier for them to lose 1 or gain 7? Lose 1 Ex. The alkaline earth metals have 2 valence electrons. Is it easier for them to lose 2 or gain 6? Lose 2 Ex. The Boron family has 3 valence electrons. Is it easier for them to lose 3 or gain 5? Lose 3 Ex. The Carbon family has 4 valence electrons. Is it easier for them to lose 4 or gain 4? Neither is easier!!

Ex. The Nitrogen Family has 5 valence electrons. Is it easier for them to lose 5 or gain 3? Gain 3 Ex. The Oxygen Family has 6 valence electrons. Is it easier for them to lose 6 or gain 2? Gain 2 Ex. The Halogens have 7 valence electrons. Is it easier for them to lose 7 or gain 1? Gain 1 Ex. The Nobel gases have 8 valence electrons(He has 2 but is full) They will not gain or lose electrons!!

Oxidation Number • The Oxidation number is the “charge” of an atom once it has gained or lost electrons to become stable!

• Alkali metals lose 1 electron – Oxidation # is +1 • Alkaline Earth Metals lose 2 electrons – Oxidation # is +2 • Boron Family loses 3 electrons – Oxidation # is +3 • Carbon Family – Oxidation # is +/- 4 • Nitrogen Family gains 3 electrons – Oxidation # is -3 • Oxygen Family gains 2 electrons – Oxidation # is -2 • Halogens gain 1 electron – Oxidation # is -1 • Nobel Gases are stable – Oxidation # is 0

Oxidation # Copy these numbers !!!!!!!

Types of Bonding 1. Ionic Bonding 2. Covalent Bonding • Involves the formation of ions by the transfer of electrons. • Ionic Bonds form between metals and nonmetals. • The + metal ion and the – nonmetal ion are attracted to each other and form a bond. • Involves the sharing of electrons. • Covalent bonds form between nonmetals and nonmetals. • Both nonmetals want to gain electrons. • Instead they will share electrons in an attempt to fill their valence shell! Na Cl

Bond Types(cont. ) 3. Metallic Bonding—involves a “sea of electrons” -between metals and metals

Lewis Dot Structures (aka Electron Dot Diagrams) • Lewis dot structures are a shorthand to represent the valence electrons of an atom. • The structures are written as the element symbol surrounded by dots that represent their # of valence electrons. • Notice that it is as if dots are drawn on imaginary Square with no more than 2 dots(valence electrons) per side!!

Lewis Dot Structures(cont. ) • Lewis structures can also be used to show covalent bonding between atoms. • The bonding electrons are placed between the atoms and can be represented by a pair of dots or a dash (each dash represents one pair of electrons, or one bond). Copy These