Transition Electron Micrograph (TEM) Chemistry Basics Transition Electron Micrograph (TEM) of atoms Oxygen (O)

All matter is made of chemical _______ ATOMS AND MOLECULES All matter is made of chemical _______ Can’t be broken down by _________ means __ occur in nature, ~__ more in labs 8 make up 99% of the stuff on Earth’s surface __ are essential to life Organisms are made mostly (95%) of 4: Oxygen (O) Carbon (C) Hydrogen (H) Nitrogen (N) Where is each commonly encountered?

Periodic table of the elements Arranged according to number of protons (more later) = ____________ Number Metals Non-metals Alkali metals

Each element is a kind of atom Bohr atom, after Niels Bohr Electrons: (-) charge Nucleus Protons: (+) charge Neutrons: (+) charge

Electrons occur in _______ or shells Inner shell (Oxygen) Outer shell Opposite charges _______ electrons to protons Pulls electrons toward nucleus Like charges ______ electrons from other electrons Keeps electrons spread out Electromagnetic repulsion among protons is overwhelmed by poorly-understood __________ Binds protons and neutrons Involves quarks and ______ __________ of neutrons and protons

Larger atoms have more ______ Each orbital has it’s maximum number of electrons 1st orbital holds 2 e- 2nd holds 8 e- Electrons in outer orbitals have ____ energy When electrons move to inner orbitals they _______ energy more energy Organisms use this to get ______ from chemical reactions

Atoms have electrically charged forms, called _____ The number of electrons(-) & protons(+) are ______ Negatively charged ion = anion Positively charged Ion = cation

Atoms can rob electrons from other atoms Atoms with many e-s in their outer orbital rob from atoms with few e-s in their outer orbital An Oxygen atom, with 7 out of 8 e-s in its outer orbital, can rob the single e- of a Hydrogen atom Resulting in 2 ions:

Chemical reactions = _____ Elements combine to form _________ Hydrogen (H) plus Oxygen (O) = _____ Sodium (Na) plus Chlorine (Cl) = _____ Compounds are held together by chemical _____

2 major categories of compounds 1. Inorganic compounds From _________ sources Have _____ bonds Ions with opposite charges are attracted cation anion Ionic bond

Table salt is inorganic Ionic bonds result in stacked blocks Form brittle ________

2. Organic compounds (more next lecture) From _____ sources Have _______ bonds Atoms ______ a pair of electrons Hydrogen lacks a neutron - unique to Hydrogen Covalent bonds are strong, ______