The Chemistry of Life Chapter 6

Matter- anything that has mass and occupies space

Atom- basic unit of matter Subatomic particles:

Protons (+) –in nucleus, 1 amuNeutrons (0) –in nucleus, 1 amuElectrons (-) –in clouds or orbitals,1/1840 amu, very very small

*amu= atomic mass unit

Element- pure substance that consists entirely of one type of atom

Compound –a substance containing two or more elements NaCl

Isotopes- elements with differing number of neutrons in the nucleus

Ex. Carbon -12, has 12 neutronsCarbon -13, has 13 neutronsCarbon -14, has 14 neutrons

Atomic Number - # of protons, equals # electrons in neutral atomAtomic Mass/ Mass Number- # of protons + # of neutrons

Reading Periodic Table

Periodic Table Practice:Element Atomic # Mass # #

Protons#

Neutrons#

Electrons

O 16 8C 6 12 6Li 7 3P 15 31Cl 35 17Ne 20 10Ni 28 31

Electron Energy LevelsElectrons orbit nucleus at different distances,

called energy levels

1st level- closest to nucleus, holds 2 electrons

2nd level- holds 8 electrons 3rd level- holds 18

Valence electrons- electrons located in the outer level, atoms stable with 8 valence electrons

Electron Dot Diagrams

Electron Dot Diagrams- only show valence electrons, electrons in outermost energy level

Why & How does Chemical Bonding Occur?

Octet Rule- atoms gain/lose/share electrons with other atoms in order to become stable/ happy with 8 valence electrons

Atoms gain/lose the least number of electrons as possible

Ex. Sodium (Na)= 1 valence electron, will lose 1 electron instead of gain 7 electrons

Ex. Chlorine (Cl)= 7 valence electrons, will gain 1 electron instead of losing 7 electrons

Ionic bondsIonic bonds- when an atom transfers an

electron to another atom

Ionic bondsIon- atoms that have become electrically

charged as a result of gaining or losing e-

Cation- (+) charge, Ex. Na+ losing e- became 1+

Anion- (-) charge, Ex. Cl-, gaining e- became 1-

Attraction holding Na+ and Cl- Ionic bond

Covalent bondsCovalent bond is when two atoms share

electrons.The number of bonds an atom can form

depend on the number of e- needed to fill its highest energy level.

H- only 1 O – accepts 2Molecules- atoms held together by covalent bonds

Water H2O