Unit 4 Atoms & Bonding

4.1: Atoms, Bonding, and The Periodic Table, 4.2: Ionic Bonds, 4.3: Covalent Bonds, 4.4: Bonding in Metals

Valence Electrons

are involved in chemical bonding (1-8)

the number of them in each atom help determine its properties

Electron Dot Diagrams

include the symbol for that element surrounded by dots, each representing one valence electrons (1-8)

1: write out the chemical symbol

2: Find the number of valence electrons

3: Draw the valence electrons in the following configurations (not more than two dots per side)

Chemical Bond

is the force of attraction that holds atoms together as a result of the rearrangement of electrons between them

Groups

are the columns

Periods

are the rows

Noble Gases

since they already have 8 valence electrons they are generally unstable

Metals

generally react by losing their valence electrons and are left w/ a stable valence shell of 8

Alkali Metals

reactive w/ water, loses their valence electrons

Non Metals

always gain never share, react by gaining or sharing valence electrons till 8

Halogens (non metals too)

only need 1 additional valence electron, so they react easily w/ other elements

Metalloids

properties of both metals and nonmetals, either lose or share electrons when they combine w/ other elements

Hydrogen

only has 1 valence electron, forms compounds with nonmetals to obtain a stable arrangement of 2 valence electrons

Ion

is an atom or group of atoms that have an electric charge. When a neutral atom loses a valence electron, it loses a negative charge. It becomes a positive ion. When a neutral atom gains an electron, it gains a negative charge. It becomes a negative ion.

Polyatomic Ion

Ions that are made w/ more than 1 atom

Ionic Bond

is an attraction between 2 oppositely charged ions.

Ionic Compound

The result of an ionic bond, they have an equal number of positive atoms and negative atoms

Chemical Formula

is a group of symbols that show the ratio of elements in a compound

Subscript

tell the ratio of elements in a compound.

what are the properties of ionic compounds?

form hard, brittle crystals that have high melting points. They conduct electrical currents when dissolved in water or melted.

Covalent Bond

the chemical bond formed when 2 or more atoms share electrons. Form between nonmetals.

Single Bond

when 2 atoms share 1 pair electrons.

Double Bond

when 2 atoms share 2 pairs of electrons

Triple Bond

when 2 atoms share 3 pairs of electrons

Molecular Compound

a compound made up of molecules containing atoms that are covalently bonded

Molecular Compound Properties

good insulators, poor conductors, lower melting points and lower boiling points.

Nonpolar Bond

a covalent bond in which electrons are shared equally, atoms pull equally, happens between identical atoms

Polar Bond

a covalent bond in which electrons are shared unequally, atoms pull unequally, happens between different atoms

Van Der Waals force

the attraction between oppositely charged atoms

Metal Crystals

are composed of closely packed, positively charged metal ions. The valence electrons drift among the ions

Metallic Bond

an attraction between a positive metal ion and the electrons surrounding it

Properties of metals

hard, dense, Shiny luster, high levels of malleability, ductility, electrical conductivity, and thermal conductivity

Luster

polished metals-metallic luster. it is due to the valence electrons, when light strikes these electrons, they absorb the light and then re-emit the light.

Malleability

rolled into thin sheets of beaten into shapes, act like this bc positive metal ions attract to loose electrons around them rather than metal ions. these can change shape. metallic bond between ion and surrounding electrons keep the metal ions from breaking apart.

Ductility

easily pulled into strands or wires

Thermal Conductivity

total energy of motion of particles in object, flows warmer to cooler (known as heat), metal conducts heat easily

Electrical Conductivity

charged particles that move conduct electric current, bc valence electrons move

Alloys

mixture made of 2 or more elements and 1 must be metal, Stronger and less reactive than pure metals

Examples: Gold Jewelry (to be stronger), Iron (to not rust)

metals

lose

nonmetals

gain

Ionic

metals and nonmetals, metals and metalloids, Transferred

Covalent

Nonmetal and nonmetal, nonmetal and metalloid, Shared

Metallic

Metal only, sea of electrons