ATOMS Proton (+) Neutron Electron(-) - + Positively charged protons and uncharged neutrons are bound together in a dense nucleus, while the negatively charged electrons move around the nucleus.

- + SUBATOMIC PARTICLES PROTON Nucleus NEUTRON NONE ELECTRON CHARGE LOCATION PROTON + Nucleus NEUTRON NONE ELECTRON - Outside Nucleus (in motion)

SUBATOMIC PARTICLES

Basic Atomic Structure Movie

Models of H, O and C Atoms Hydrogen Atom 1 proton 1 electron Oxygen Atom 8 protons 8 neutrons 8 electrons Carbon Atom 6 protons 6 neutrons 6 electrons

Isotopes Isotope - atoms of the same element that differ in their number of neutrons.

Valence Electron Outer Shell Electron from hydrogen Electron from carbon Valence Electron - an electron that is associated with an atom that can participate in the formation of a chemical bond.

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Chemical Compound Chemical Compound - a substance formed by the chemical combination of two or more elements in definite proportions.

Chemical Bonds Chemical Bond - the attraction, sharing, or transfer of outer shell electrons from one atom to another.

Types of Chemical Bonds Ionic Bond Ionic Bond - the transfer of valence electrons between atoms. Generates two oppositely charged ions.

Types of Chemical Bonds Covalent Bond Covalent Bond - pairs of electrons are shared by atoms.

Types of Chemical Bonds Hydrogen Bond Hydrogen Bond - a weak attraction occurring between a slightly positive hydrogen atom in a molecule and a nearby slightly negative atom of another molecule.

Water

Water In a water molecule, each hydrogen atom forms a covalent bond with the oxygen atom.

Water is a Polar Molecule Water has positive charges on one side and negative charges on the other side

Properties of Water Water is polar Water resists temperature changes Water expands when it freezes Water sticks well to itself (cohesion) Water sticks well to other things (adhesion) Water has a high level of surface tension

What is Surface Tension? Surface tension is the cohesive force between liquid molecules.

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Sinkin’ Lincoln Lab Objectives: Measure the surface tension of different liquids. Identify independent and dependent variables. Plot a graph with the data collected. Learn about polar molecules and surface tension.

Label the positive and negative charges on the water molecules. Draw three water molecules. Draw dotted lines showing where the hydrogen bonding occurs. Label the positive and negative charges on the water molecules. H H H

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