Ch 7 Notes

Atoms ‘building blocks’ Element ‘one kind of atom’ Compounds ‘different kinds of atoms’ Shown w/ Symbols Shown w/ Formulas Molecule two or more atoms bonded together, atoms can be the same or different

Subatomic Particles & Their Charges protons = positive electrons = negative neutrons = neutral Practice – indicate the # of P+, E -, & N o for each element: Na, Al, K, Fe

Valence Electrons # of electrons found in the outermost energy level determines how the element reacts chemically What are the # of electrons in the 1st four energy levels? Which group of elements are NOT reactive b/c their outer energy level is full?

What is Chemical Bonding? Combining atoms of two or more different elements Forms a new substance Determined by the # of valence electrons What are the types of bonds?

Ionic Bonding Electrons are given up or received Opposite charges attract The positive atom (cation) bonds with the negative atom (anion)

Types of Ions Cation (+) & Anion (-)

Ionic Bonding Atom X has few valence electrons & tends to lose those electrons – this creates a positive charge Atom Z has many valence electrons & tends to gain more electrons to fill its outer shell – this creates a negative charge

Ionic Bonding of Na & Cl

The more electrons to move, the more energy required.

The Crystal Lattice Arrangement of ions is specific to that compound Created by ionic bonds

Identifying Bonds 1.Two nonmetal atoms usually form covalent bonds. 2.A metal and a nonmetal atom usually form ionic bonds.

Covalent Bonding Electrons are shared between atoms These shared electrons fill up the valence shell of each atom Elements that exist in nature as two atoms of the same element covalently bonded are called DIATOMIC elements

Covalent Bonding of Water

Covalent Bonding creating C 2 H 6

Electron Dot Diagram

Polyatomic Ions a group of covalently bonded atoms that act like a single atom when combining with other atoms usually form ionic bonds Copy the charts of common polyatomic ions on page 186

Metallic Bonding metallic solids are solids made of entirely one metal element bonds are formed between two or more metal atoms the outer electrons that are easily given up form a common electron cloud

Oxidation Number the # of electrons an atom gains, loses, or shares when it forms chemical bonds Example: Na (+1) & Cl (-1) CH4 … C(+4) & H (-1) the sum of oxidation numbers of the atoms must equal zero