Bonding & the Periodic Table

Valence Electrons and Bonding - Atoms, Bonding, and the Periodic Table Valence Electrons and Bonding The number of valence electrons in an atom of an element determines many properties of that element, including the ways in which the atom can bond with other atoms & it determines the way it reacts

Fundamental Rule All atoms want to look like the noble gasses So they either want to get rid of all of their valence electrons, or accept more electrons.

Electron Configuration Group I Electron Configuration Group VIII Group II Period 1 Group III Group IV Group V Group VI Group VII 1 2 H He 3 4 5 6 7 8 9 10 Period 2 LI Be B C N O F Ne 11 12 13 14 15 16 17 18 Period 3 Alkaline (1) (Very Reactive) Noble Gasses (8) (Not Reactive) Alkali Earth (2) (Reactive) Boron Family (3) Na Carbon Family (4) Mg Nitrogen Family (5) Al Oxygen Family (6) (Reactive) Si Halogens (7) (Very Reactive) P S Cl Ar Notice the valence electrons. Each one wants outer shell filled. Group 1 wants to get rid of their electrons – Group 7 wants to keep it. Group 8 keeps all and never shares. © Beadle, 2009

Electron Configuration Group I Electron Configuration Group VIII Group II Period 1 Group III Group IV Group V Group VI Group VII 1 2 H He 3 4 5 6 7 8 9 10 Period 2 LI Be B C N O F Ne 11 12 13 14 15 16 17 18 Period 3 Alkaline (1) (Very Reactive) Noble Gasses (8) (Not Reactive) Alkali Earth (2) (Reactive) Boron Family (3) Na Carbon Family (4) Mg Nitrogen Family (5) Al Oxygen Family (6) (Reactive) Si Halogens (7) (Very Reactive) P S Cl Ar Point out the valence electrons. Each one wants outer shell filled. This is what causes a reaction. Also note the empty spaces – how every atom wants 8 (filled) © Beadle, 2009

- - - - - - - - - - - - - - - - - - - Metals v. Non Metals 17p+ 11p+ Becomes Positive (+) Becomes Negative (-) - - - - 11p+ - - - - - 17p+ - - - - - - - - - - Sodium Na (11): Metal Gets rid of Electrons Chlorine (17): Non Metal Accepts Electrons 11 P & 10 E- = +1 17 P & 18 E- = -1 © Beadle, 2009

Metals+ Get Rid of Electrons Non-Metals- Accept Electrons – Gain or Accept e- Metalloids Metals+ Get Rid of Electrons

Chemical Bonds Cause Chemical Reactions Ionic Metal + Non-Metal Co-valent Non-Metal + Non-Metal Metallic Metal + Metal

- Ionic Bonds Ions and Ionic Bonds When an atom loses an electron, it loses a negative charge and become a positive ion. When an atom gains an electron, it gains a negative charge and becomes a negative ion.

- - - Ionic Bonding M+NM 17p+ 11p+ Becomes Positive (+) Becomes Negative (-) - 17p+ - - 11p+ Sodium Na (11): Metal Gets rid of Electrons Chlorine (17): Non Metal Accepts Electrons 11p+ + -10e- = +1 17p+ + -18e- = -1 © Beadle, 2009

- - - - - - - - - - - - - - - - - - - Ionic Bonding M+NM 17p+ 11p+ Becomes Positive (+) Becomes Negative (-) - - (-) - - - 11p+ (+) - - - - 17p+ - - - - - - - - - - Sodium Na (11): Metal Gets rid of Electrons Chlorine (17): Non Metal Accepts Electrons 11p+ + -10e- = +1 17p+ + -18e- = -1 © Beadle, 2009

Example: Salt Crystal

Properties of Ionic Compounds - Ionic Bonds Properties of Ionic Compounds In general, ionic compounds are hard, brittle crystals, high melting points, conduct electricity when dissolved/melted

Covalent Bonding NM + NM - - - - - - 8p+ 8p+ - - - - - - Oxygen (8) Oxygen (8) O2 © Beadle, 2009

Covalent Bond Examples Ethyl Alcohol Methane Sugar

Properties of Covalent Bonds Covalently Bonded Molecules: Usually liquid/gas at room temp. Sometimes you may find it in crystal form Have low melting/boiling points Have low viscosity Have low density Do not conduct electricity when dissolved.

- - Metallic Bonding M + M 11p+ 11p+ (-) (-) (+) (+) - Bonding in Metals Metallic Bonding M + M A metal crystal consists of positively charged metal ions embedded in a “sea” of valence electrons. (-) (-) - - (+) (+) 11p+ 11p+ © Beadle, 2009

Properties of Metals The “sea of electrons” model of solid metals explains their ability to conduct heat and electricity…

Properties of Metals The “sea of electrons” model of solid metals explains their ease with which they can be made to change shape…

Properties of Metals Luster Gold in an astronaut’s face shield reflects sunlight, protecting the wearer’s eyes. The “sea of electrons” model of solid metals explains their luster.

Chemical Reactions Chemical Reactions happen because of bonding.

Chemical Change (Reaction) Chemical reactions occur when old bonds break and new bonds form.

Chemical Change (Reaction) Chemical reactions involve two main kinds of changes that you can observe – formation of new substances and changes in energy.