Standard d. Explain the impact of water on life processes (i.e., osmosis, diffusion).

Before we get to the standard, you need to understand the basics of…..

BIOCHEMISTRY

Biochemistry is…. The Chemistry of Life Cell (skin cell) basic building block of living organisms (life) Atom basic building block of matter

Atom: the basic unit of matter Elements: simplest form of a substance CHEMISTRY OF LIFE Atom: the basic unit of matter composed of protons, neutrons, and electrons Elements: simplest form of a substance

Parts of an atom Subatomic particles: parts of an atom Neutrons and Protons (+) are located in the nucleus of an atom. Electrons (-) orbit around the nucleus

What is an Isotope? Iso means same Atoms of the same element that HAVE A DIFFERENT NUMBER OF NEUTRONS   

ISOTOPES (iso- = same) Some isotopes are radioactive. This means that their nuclei is unstable and will break down at a CONSTANT RATE over time. There are several practical uses for radioactive isotopes: CARBON DATING TRACERS KILL BACTERIA / CANCER CELLS

Quick check Fill in the blanks below as a class: The smallest unit of matter is called an __________. An atom is made up of protons, ____________ and _____________. The simplest form of a substance is called an ____________. If an isotope is radioactive, then the nucleus will ________________ over time.

So, what elements are essential for life?

These are!!! Carbon, Hydrogen, Oxygen, Phosphorous, Nitrogen, Sulfur

Um….. Question! How do elements combine to make up everything on Earth!

Answer! Through chemical bonding This makes molecules and compound!

MOLECULES and COMPOUNDS A molecule is formed when two or more atoms join together chemically. A compound is a molecule that contains at least two different elements. All compounds are molecules but not all molecules are compounds. Ex: water, salt, glucose, carbon dioxide

CHEMICAL BONDS Chemical bonds hold the atoms in a compound (aka molecule) together. There are 2 types of chemical bonds IONIC and COVALENT

IONIC BONDS (think magnets) Occur when 1 or more electrons are TRANSFERRED from one atom to another. Loss of electron=positive. Gain of electron=negative These newly charged atoms are now called IONS Example: Na+ ion bonds to a Cl- to make NaCl (salt) THIS MAKES COMPOUNDS!

COVALENT BONDS Occur when electrons are SHARED by atoms. **These new structures that result from covalent bonds are called MOLECULES SHARING IS CARING!

Quick Check Are all molecules compounds? (yes or no) The transfer of electrons is __________ bonding The sharing of electrons is _____________ bonding

Now what is the deal with water? Why is it important for life?

Water is special! Water is made up of 2 hydrogens and 1 oxygen The oxygen is negative and unequally shares the electrons from the hydrogen, thus making hydrogen positive

So what’s the big deal? Because oxygen is “electronegative” it creates poles on the water molecule. Makes it act like a magnet This property is called POLARITY.

Hydrogen bonds The bond formed between water molecules is called a hydrogen bond. Hydrogen bonds are very weak bonds

Properties of water Water has 4 main properties Cohesion Adhesion High specific heat High heat of vaporization

Properties of water: Cohesion Cohesion: attraction between particles of the same substance This is why water sticks to itself Creates surface tension

Properties of water: Adhesion Adhesion: Attraction between two different substances Allows water to stick to objects Enables transpiration in plants

Properties of water: High Specific Heat High specific heat: amount of heat needed to change a substance 1 degree Celsius Water resists change Water can absorb and release heat with little change in overall temperature

Properties of water: High heat of vaporization Heat of vaporization: amount of energy needed to change a substance from a liquid to a gas Hydrogen bonds must break This breaking removes a lot of heat Causes a global “blanket”; helps cool earth!!!! 