Chemistry Review Matter: Takes up space and has volume Do not write slide Matter: Takes up space and has volume Element: Different types of matter Atom: Smallest example of an element Protons: + , 1amu , nucleus Neutrons: no charge , 1amu, nucleus Electron: - , not significant, electron cloud

Chemistry Review Atomic #: number of protons (electron if neutral) Do not write slide Atomic #: number of protons (electron if neutral) Atomic Mass: protons + neutrons Unique symbol Isotope: same element, different # neutrons. Ion: different number of electrons

The Properties of Water

Types of chemical bonds IONIC BONDS: transfer electrons ex. NaCl-Sodium Chloride

COVALENT BONDS -Share electrons equally. ex. H2

Size/electronegativity relationship

Polar Covalent bond Share electrons unequally. ex. H2O

HYDROGEN BOND- weak attraction between the positive end of one water molecule and the negative end of another water molecule. ex. H2O-H2O

Water Water is a polar molecule because electrons spend more time near the oxygen, making the O slightly negative and the H slightly positive. Properties of water: Adhesion: The attractive force between molecules of different materials. Ex: water drop on glass. Cohesion: The attractive force between molecules of the same material. Ex: cohesion between water molecules

adhesion and cohesion cause: Capillary action – waters moves up against gravity. Surface tension: the cohesion of water molecules at the surface of a body of water.

High specific heat- Takes a lot of heat to raise the temperature of water and a lot of heat must be lost to lower its temperature.

Expands upon freezing- At 4ºC, it expands forming hexagonal ice crystals which make it less dense than liquid water The floating ice is an insulator between the water and cold air

Universal solvent -because of the slight charges, there is attraction to other molecules, giving water the ability to dissolve molecules.

pH scale Indicates the acidity or alkalinity (basic) of a solution. Acid = High H+ concentration HCl  H+ + Cl- Basic = Low H+ concentration NaOH  Na+ + OH-

Properties of Water Lab Do not write slide Part I : Hold tight How much water (mL) is in a drop of what? Comparing substances Part II : Who’s the hottest? ( Class Demo) Which heats up fast sand vs. water Part III: Temperature vs Solubility Does different temperatures dissolve different amounts. Part IV: Temperature vs. Density