Chapter 2

The Chemistry of Life2A Basic Chemistry

Cave of Crystals

• Found 1000 feet deep in Mexico.• Those are ice cooling suits.• Crystals are made of Gypsum.

Matter

Matter is anything that occupies space and has mass.

What are the three states of matter?1. Gas2. Solid3. LiquidEach state of matter is due to the varying amounts

of energy possessed by that matter.

Matter

• 109 known elements

• Elements are pure substances that cannot be furher broken down into simpler substances.

• Ex. keep cutting gold in half over and over again until the piece would no longer be gold.

Atom

• smallest unit of an element that still is that element.

• The name comes from Greek to mean indivisible.

Periodic Table

• An arrangement of the elements according to atomic structure.

• The next slide shows the periodic table of elements.

Atomic Structure

• The atom is like the solar system.

• Nucleus has neutrons (no charge) and the protons (positive charge).

• Electrons (negative charge) constantly circles the nucleus within orbits at varying distances.

Atomic Structure

• Most of the atom is empty space between the nucleus and the electrons of atoms.

• The opposing forces of the protons and the electrons hold the atom together.

Atom parts

Atomic Structure

• Electrons = Protons • Positive and negative charges cancel each

other making the atom charge zero. This is for ATOMS!!

• 1 proton and 1 electron then this atom is what?

• Hydrogen

Atomic Number

• # of protons in the nucleus.

• All atoms of a particular element have the same number of protons.

• If the proton number changes, then the actual element changes!!

Atom: smallest unit of an element made of…

p+= Protons: + charged particles in nucleus

n= Neutrons: neutral particles in nucleus

e-= Electrons: - charged particles around nucleus

Normally atoms are neutral: p = e

Ion: a + or - charged atom

Atomic Mass

• Is the mass of the protons and the neutrons together.

Chemical Bonding

• Most atoms are unstable (and lonely) and want to bond with another.

• An atom is only stable when the outer most shell of electrons is full.

Electron shell

• The first orbit or shell can only hold two electrons.

• The second shell can hold 8 electrons.• The third shell can hold 18 electrons, but is

stable with only 8. • Each shell after that holds more and more

electrons, but all act full with eight.

Electron shells

Essential Elements of Life

• Oxygen O 65% of body weight• Carbon C 18% of body weight• Hydrogen H 10% of body weight• Nitrogen N 3% of body weight• Calcium Ca 2% of body weight

Essential Elements of Life

• Less common, but still essential elements• Phosphorus P• Potassium K• Sulfur S• Chlorine Cl• Sodium Na• Magnesium Mg

Trace Elements

• Copper Cu• Fluorine F• Iron Fe• Iodine I• Zinc Zn

Elements of Life

What element is this?

Carbon

Oxygen

What element is this?

What element is this?

What element is this?

Noble Gases

• Atoms with naturally full outer shells, so they are very stable.

• Helium, neon, argon, and etc that are located on the right side of the table.

Chemically active

• Atoms that give and take or share electrons in order to become more stable.

Ionic Bonding

• Chlorine is a non-metal. If chlorine gains an electron is becomes stable.

• Sodium is a metal. If Sodium loses an electron it becomes stable.

• This combination forms a new substance – table salt. NaCl It is more stable than the two elements that formed it.

Ionic bonding

Ionic Bonding

• An atom that loses an electron becomes a positive ion.

• Atom that gains an electron becomes a negative ion.

• Na loses an electron so it becomes a positive charge

• Cl gains an electron so it becomes a negative charge

Ionic Bond

• The positive ion Na is attracted to the negative ion Cl.

• This is an ionic bond, because it is the attraction of two ions!!!

Covalent Bond

• sharing electrons • “Co” means to share and they are sharing the

valence. • Water, H2O example

• Hydrogen shares its electron with Oxygen.• P. 41 in book.• Very strong bond!!!

Covalent Bond in water

Compounds

• Substance made of two or more elements.

• examples: CO, H2O, NO

Molecule

• Smallest unit of a compound.

Molecular Formulas

• Glucose is C6H12O6 Molecular Formula

• Structural Formula

Chemical vs. Physical Change

Chemical Change• definite proportions• new compounds formed• energy is involved

Physical change • change in state• appearance• combination w/ other substances• Mixture – 2 substances combine w/o chemical

bonding. Sand and water ex.

Energy

• The other component to the physical universe.• Energy is the ability to do work.• Two Types

– Kinetic is the energy of motion ex. heat, light, movement

– Potential is stored energy waiting to be kinetic energy. Battery or an object about to fall off a ledge.

Energy

Energy Converted

• As you see potential energy can be converted or changed into kinetic. The bike rolling down the hill is that conversion.

Potential Kinetic

• Kinetic energy is also converted into potential (stored) energy in plants.

Kinetic Potential

Thermodynamics

• 1st Law – Energy is neither created nor destroyed. It can change forms.

• 2nd Law - some energy is unusable. entropy

Kinetic Energy of a Molecule

• The amount of thermal energy determines how fast its molecules move and thus its physical state. Gas, liquid or solid.

Potential Energy of a Molecule• Potential energy of a molecule: stored in its

chemical bonds

2 kinds of chemical rxn

1) Endothermic rxn Requires or absorbs heat energy A + B +

energy C + DRemember what Endo means?

2) Exothermic rxn liberates heat energy A + B energy + C + DRemember what exo means?

Acids and Bases

When dissolved in H2O…

Acid: releases hydrogen ions (H+) Base: releases hydroxyl ions (OH-)

When an acid & base are put together they neutralize each other to make a salt & H2O

pH: acidity or alkalinity of a sol’n “power of hydrogen”

Internal & external pH of living things is important…

pH: * blood pH * brain pH * stomach enzymes * acids can harm lungs* acid rain - clear lake w/ no normal life - deformed fish - diseased plants

Buffer will combine with excess H+ or OH-

Species Survivability in acidic environments

diffusion: mvt of molecules from an area of [high] to an area of [low]

equilibrium: equal []

osmosis: diffusion of water through a semipermeable membrane

Diffusion pressure: the pressure for diffusion to occur

diffusion will happen faster * the greater the difference in [] * As heat increases

osmosis: diffusion of H2O through a semipermeable membrane

• membrane is only permeable to H2O

• the correct solute (dissolved substance) in the cell is critical

Some rxn occur immediatelyex: Na + Cl NaCl

Some rxn need energy to start them

activation energy:energy needed to start a rxn

Catalyst: effect the rate of rxn but are not changed in the rxn Enzymes: our body’s catalysts,energy is released in small usable amounts

solutions: homogeneous mixtureex: sugar water

solute: dissolved substance

solvent: what the solute is dissolved in

water is the universal solvent

suspensions: particles do not dissolve; a liquid mixture that separates