Biochemistry + Water + pH

Biochemistry:

Study of chemical processes and substances in living organisms that explains how molecules like proteins, DNA, and enzymes work together to keep life functioning

Atoms: (3)

Smallest units of matter - makes up all substances (including living things)

Very small

First used by Greek philosopher Democritus about 2500 years ago

What atoms are made of: (5)

Protons - positively charged

Neutrons - no charge (neutral)

electrons - negatively charged

Protons and neutrons form the nucleus in the atom’s center and have a similar heavy mass

Electrons are in constant motion in the space outside/surrounding the nucleus and have a light mass

Electron Shells: (3)

Electrons are arranged in shells around the nucleus where different rings hold different amounts of electrons

Outermost shell = valence shell, electrons here are responsible for the atom’s chemical properties

Models of this are called Bohr models

What is the charge of an atom?

Atoms are usually neutral because they have an equal number of protons and electrons, which have opposite charges

Elements: (3)

Pure substance = only 1 type of atom

More than 100 elements known (both naturally occurring and man made)

Represented by a 1 or 2 letter symbol on the periodic table

Periodic Table: (5)

Organizes elements based on reactivity, which depends on the number of valence electrons

Groups = columns, where elements in the same group have the same amount of valence electrons (each group has 1 more electron in its valence shell)

periods = rows, where elements have the same number of electrons shells

group 8 = least reactive because their shells are full (Noble gases), groups 1 + 7 = most reactive because they need electrons to fill their shell (7) or have some to give away (1)

First assembled by Dimitri Mendeleev

Periodic Symbols: (2)

Atomic number = number of protons, top left corner (usually same as electrons)

Atomic mass = protons + neutrons in the nucleus (extra mass is due to isotopes)

Isotopes: (3)

Atoms of the same element that differ in their number of neutrons (ex. C-12, C-13, C-14)

Identified by their mass number

Because isotopes have the same number of electrons, they have the same chemical properties

Radioactive Isotopes: (2)

Have unstable nuclei that break down at a constant rate over time

Radiation given off may be dangerous but also has uses like cancer treatment, biological “labels”, and radiocarbon dating

Molecules and Compounds: (5)

Molecules = chemical combination of 2 or more elements

Compound = combination of 2 or more DIFFERENT elements

All compounds are molecules but not all molecules are compounds

Held together by bonds

Chemical formulas = composition of compounds

Bonds: (3)

Ionic bonds = formed by a complete transfer of electrons from a metal to a nonmetal

Covalent (nonpolar) bonds = formed by the equal sharing of electrons between nonmetals

Polar covalent bonds = formed by the unequal sharing of electrons between nonmetals

Ions: (4)

When molecules bond they create different charges that affect different substances

They are atoms with an electrical charge because it has an unequal number of protons and electrons

Anion = negatively charged atom in a bond (gains electrons, usually non-metals)

Cation = positively charged atom in a bond (loses electrons, usually metals)

Water Molecules: (4)

Oxygen (with a heavier mass and more electrons) has stronger attraction for electrons than hydrogen (with a lighter mass and less electrons)

2 hydrogen atoms share their electrons with oxygen

Oxygen has a slight negative charge, while hydrogen atoms have a slight positive charge, which makes it polar and causes attraction

Bond formed = hydrogen bond (not as strong as ionic or covalent, but the strongest that can form between molecules) - responsible for water’s unique properties

CAVSS (water’s properties):

Cohesion

Adhesion

Vaporization point

Specific heat

universal Solvant

Cohesion: (2)

Ends of water molecules attract each other to make a net of hydrogen bonds that stick together

Responsible for surface tension

Adhesion: (2)

Attraction between molecules of different substances (ex. water sticking to windshield)

Responsible for capillary action - movement of water in a tube against gravity (in plant xylem?)

Vaporization Point:

High amount of energy is required to turn just 1 gram of liquid water into gas vapor

Specific Heat: (2)

High amount of energy is required to change the temperature of water by just 1 degree Celsius

Allows water to remain (relatively) the same temperature even when the air gets cold (ex. pool)

Universal Solvent: (2)

Solute (substance that’s dissolved) + solvent (substance in which the solute dissolved) = solution (homogeneous mixture - often chemically combined)

Water = universal Solvent because it can dissolve ionic compounds and other polar molecules

Other Combinations: (2)

Mixture = material composed of 2 or more elements or compounds that are mixed together but not chemically combined (ex. salt and pepper)

Suspension = mixture of water and non-dissolved material (which breaks into extremely small pieces while the movement of water keeps it from settling)

pH Scale: (6)

Measures the acidity or alkalinity (base) of different substances

pH = power of Hydrogen - indicates how many hydrogen ions (H+) are present

Scale moves from 0 (super acidic) to 14 (very alkaline)

Water = neutral (makes perfect Solvent) - neither acidic nor alkaline at 7 pH

Each number on the scale is 10x more acidic or alkaline than previous

Acidity of substances affects interactions with other matter