Earth & Space Science Chapter 3 Matter and Change

Atomic Structure Proton – Positive charge, mass = 1 amu – Found in nucleus Neutron – Neutral charge, mass = 1 amu – Found in nucleus Electron – Negative charge, very small mass – Found in energy levels (layers) orbiting the nucleus – Valence (outside) level is most important!

Model of an Atom Electrons are shown in energy levels: First energy level can hold 2 electrons, Second energy level can hold 8 electrons Third energy level can hold 18 electrons

Isotopes Draw a model of a chlorine-35 atom and a chlorine-37 atom. Hints: Chlorine has 17 protons Mass = protons + neutrons Electrons = protons

Elements Most abundant elements in Earth’s crust: – Oxygen(it’s a gas—how can it be in the crust?) – Silicon – Aluminum – Iron – Calcium Most abundant elements in the universe: – Hydrogen – Helium Where can H and He found?

Chemical Bonds Covalent: atoms share valence electrons – Covalent bond = molecule – Unequal sharing creates a polar bond (behaves like a tiny magnet) – Ex: H 2 O Ionic: atoms transfer valence electrons – Lose electron(s)  positive ion – Gain electron(s)  negative ion – What determines whether an atom gains or loses and how many are gained or lost?

Metallic bonds

Symbols and formulas 2H 2 + O 2  2H 2 O Identify products and reactants. How many different kinds of molecules? How many different kinds of elements? How many atoms of each element? Explain the difference between a mixture and a compound.

Mixtures Homogeneous – Uniform throughout – Stays mixed – Ex: air, magma, sea water, brass Heterogeneous – Not uniform – Ex: soil, beach sand, Italian dressing

pH 0-14 below 7 = acid 7 = neutral Above 7 = basic or alkaline

States of Matter Solids – Definite shape and volume – Crystalline or glass Liquid – Definite volume, indefinite shape Gas – No definite shape or volume Plasma – Stars, lightning, neon signs

Changes of State

Conservation Laws The Law of Conservation of Matter: Matter cannot be created or destroyed, but it can be changed from one form to another. The Law of Conservation of Energy (1 st law of Thermodynamics): Energy cannot be created or destroyed, but it can be changed from one form to another.