Materials Section A

Materials What are some common materials or resources that you use everyday?

Properties Physical Properties – properties that can be observed visually Ex. Color, luster, density, odor Physical Change – the material remains the same, but has changed form Ex. Tear a piece of paper

Properties Chemical Change – when a substance changes into a completely new and different substance Ex. Rust, copper buildings, burning Chemical Properties – relates to the kind of chemical changes it can undergo Ex. Reactivity

Properties Luster – how shiny a metal is Ductile – can be drawn into wires Malleable – Pounded into sheets Conductivity – electrical current can be passed

Strike It Rich Lab

The Elements The Element and the Periodic TableThe Element

Materials Terms Atomic Number – small number on the table, distinguishes atoms Mass Number – larger number on the table, total number of protons and neutrons in an atom, this number is an average Nucleus – center of an atom, contains protons and neutrons Isotopes – atoms with same number of protons but different number of neutrons (so they have different masses)

Trends Atomic Radius - atoms decrease in atomic size as you move left to right across a period, caused by the increasing positive charge in the nucleus atoms increase as you move down a group, the outer electrons move further and further from the nucleus this makes the atoms larger

Trends Ionic Radius - Ions increase in size as you move left to right across a period, then in group 5 and 6 the radii become massive and then decrease again Ions increase in size as you move down a group

Trends Ionization Energy - the energy required to remove an electron from a gaseous atom (think of this as how strongly an atom's nucleus holds onto it's valence electrons Ionization Energies generally increase as you move left to right across a period, and generally decrease as you move down a group

Trends Electronegativity - indicates an elements ability to attract electrons Electronegativity decreases as you move down a group and increases as you move across a period

Happy Atoms octet rule - states that atoms tend to gain, lose, or share electrons in order to acquire a full set of eight valence electrons, they are then "happy" Atoms are always “dealing” electrons to make each other happy, this is what creates bonds