UNIT 1 TOPIC 1: Structure of Water and Hydrogen Bonding

Matter

Anything that has mass and takes up space

Element

A substance that cannot be broken down into other substances by chemical reactions

Compound

A substances consisting of 2 or more different elements combined in a fixed ratio

Octet Rule

elements will lose, gain, and share electrons to ensure that their are 8 valance electrons for stability

Capillary Action

the upward movement of water due to the forces of cohesion, adhesion, and surface tension

Chemical Bonds

An attractions between two atoms, resulting from the sharing or transferring of valance electrons

Hydrogen Bonds

The partially positive hydrogen atom in one polar covalent molecule will be attracted to an electronegative atom in another polar covalent molecule

Covalent Bonds

When two or more atoms share atoms share electrons. (Usually between two non metals)

NON POLAR- Electrons are equally shared AND POLAR- Electrons are unequally shared

ie-H2O CO2

Single bond: 1 pair of shared electrons

Double bond: 2 pairs of shared electrons

Triple Bond: 3 pairs of shared electrons

Ionic Bonds

The attraction between oppositely charged ions. (Usually between a metal and non metal)

ie- NaCl and LiF

Metal transfers electrons to non metal

Cohesion

Attraction of molecules for other molecules of the same kind.

i. Hydrogen bonds between H20 molecules hold them together and Increase cohesive forces.

ii. Allows for transport of water and nutrients against gravity in plants.

iii. Responsible for surface tension

Electronegativity

The measure of an atom's ability to attract electrons to itself.

Increases going to the right up. F is the most electronegative element.

Adhesion

The clinging of one molecule to a different molecule.

i. Due to the polarity of H20

ii. In plants, this allows for water to cling to the cell wall to resist the downward pull of gravity

Atomic Mass

of protons plus neutrons averaged over all isotopes

Solute

A substance that is dissolved in a solution

Solution

Homogeneous mix of 2 or more substances

Solvent

Dissolving agent in a solution

Valance Electrons

The electrons located at the outermost shell of an atom.

Group has the same number of these (vertical)

Molecule

The smallest particle of a substance that has all of the physical and chemical properties of that substance.

Acid

any hydrogen-containing substance that is capable of donating a proton (hydrogen ion) to another substance

-neutralizes alkalis, dissolves some metals, and turns litmus red; typically, a corrosive or sour-tasting liquid of this kind.

Base

a molecule in an aqueous solution that can accept protons or donate electrons. Bases are usually bitter to taste, slippery to touch, and have a pH greater than 7 on the pH scale.

Identify the elements that make up all living matter

Carbon,Hydrogen,Nitrogen,Oxygen,Phosphorous, and sometimes Sulfur

How are hydrogen bonds different from other types of bonds

They are very weak and can be inter or intramolecular. They can form, break, and re-form with great efficiency

How does electronegativity affect the interactions between water molecules?

Because oxygen is more electronegative than hydrogen, the oxygen atom in H2O pulls electrons toward itself, resulting in a partial negative charge on the oxygen atom and a partial positive charge on the hydrogen atoms.

Imagine if Oxygen and Hydrogen had the same electronegativity, what would that do to the properties of water?

If the oxygen and hydrogen had equal electronegativity, the water molecules would lack polarity, resulting in no hydrogen bonding between water molecules.

Describes the properties of water.; give an example of each.

1. Polarity: unequal sharing of the electrons make water a polar molecule

2.Cohesion: Attraction of molecules for other molecules of the same kind.-surface tension

3.Adhesion: The clinging of one molecule to a different molecule

4.Calipallary Action: the upward movement of water due to the forces of cohesion, adhesion, and surface tension

5.Temp Control: Water resists changes in temp bc heat has to be absorbed to break hydrogen bonds but heat is released when hydrogen bonds form

6.Evaporative Cooling: Water has a high heat of vaporization

7.Density: As water solidifies it expands and becomes less dense due to hydrogen bonds. When water is cooled molecules move too slowly to break the bonds

8.Solvent: Universal solvent- water will form hydrogen bonds with sugars and proteins to dissolve them

Describe 2 ways in which the properties of water benefits organisms

Its less dense form of ice provides a sheet over water in lakes and rivers allowing marine life to thrive under the ice.

Adhesion, Cohesion, and Capillary action are important for transporting water and nutrients in plants