Download Chemistry Overview

Chemistry
Overview
Elements
• Element: pure substance that can’t be
broken down into simpler substances
• Element Symbols
– 1-3 letters
– Begin with 1 capital letter
– Some based on Latin names
• Ex/ gold = Au for Aurum
iron = Fe for Ferros
Structure
Atoms
• Smallest particle identified as an element
• Dif. atomic structures = different elements
• Atom is made of 3 particles
– Proton
– Neutron
– Electron
Atomic Structure
1. Nucleus – responsible for element’s ID
•
•
Proton – positive charged particle
Neutron - neutral charged particle w/ = mass
as proton
2. Electron cloud – surrounds the nucleus
•
•
Electron – negatively charged
Revolves around nucleus
More Atomic Structure
• Electrons arranged into energy levels
(layers)
• Valence electrons – electrons on outer
energy level (layer)
– Responsible for bonding between atoms
– Responsible for the reactivity of elements
An Atom
Elements on the Periodic Table
Calculating Atomic Structure
Atomic # = # of protons in nucleus
# of protons = # of electrons
# Neutrons = Atomic mass - # protons
Combining Elements
• Compounds – 2 or more elements
chemically combined (bonded)
• Why bond?
1. Atoms bond to become stable
2. It requires a full outer shell to be stable
3. 8 valence electrons = an octet
Metals vs. Nonmetals
Types of bonds
Covalent bonds – bonds btwn two nonmetals
Types of bonds
Ionic bonds – bonds btwn a nonmetal & metal
Types of bonds
Metallic bonds – bonds btwn two metals
Mixtures
• Mixtures - 2 or more elements occupying the
same space
– Homogeneous mixtures – substances can’t be
easily identified
• Ex/ Kool-Aide, coffee, paint
– Heterogeneous mixture – substances can be
easily identified
• Ex/ chicken noodle soup, cereal, & the atmosphere