The Nature of Matter

The Atom

• Extremely small – 100 million = 1 centimeter

• Subatomic particles – Proton - positive– Electron - negative– Neutron - neutral

Elements

• Pure substance that consists entirely of one type of atom

Isotopes

• Atoms of same element that differ in the number of neutrons they contain

• Radioactive:– Nuclei are unstable– Break down at a

constant rate

Used for fossil dating

Chemical Compounds

• Substance formed by 2 or more elements– Ex. Water H2O, NaCl

Chemical Compounds• A force that joins atoms together is called

a chemical bond• Every compound is represented by a

chemical formula that identifies the elements in the compound and their proportions– H2O– H2O2

Electron configuration

• Electrons are found in orbitals around the nucleus

• Follows the octet rule– 1st orbital (or shell) max electrons = 2– 2nd orbital – max electrons = 8– 3rd orbital – max electrons = 8

Chemical Bonds

• Valence electrons – those electrons available to form bonds (outer most electrons)

• Ion – charged particle• Ionic bond – one or more electrons are gained

or lost (ex: salt)– Lose electron – become +– Gain electron – become -

Covalent Bonds

• Atoms share electrons to fill outer shell

• Molecule – atoms joined by covalent bonds– Smallest unit of most compounds

Covalent Bonds• An element becomes stable when its outer

electron level is full• Give two examples of molecules formed

from covalent bonds:– carbon dioxide – water

Other Bonds• Hydrogen bonds- a weak chemical

attraction between polar molecules– Ex: water molecules

Other Bonds

• Van der Waals forces- slight attraction between oppositely charged regions of nearby molecules (ex-gecko feet)– Not as strong as ionic or covalent bonds

Water• Water is a major component of cells• Nearly 80% of your body is made of water• What properties of water make it such an

important substance for life?– Water stores heat efficiently– Water sticks to itself and other substances

Water

• Is a polar molecule– Due to its electrons being shared unequally– The oxygen has a much stronger pull on the

electrons than the hydrogens do– We can show this with (+) and (-)

Polar- Magnets

Polar vs Nonpolar

• Polar substances mix together (water) • Nonpolar substances mix together (oil)• Polar and nonpolar substances do not mix

together (water and oil)

Water- Hydrogen bonding

• Due to slight negative and positive charges

• Gives water many of its unique properties (cohesion)– Allows it to “stick” together– forms droplets and thin film– Surface tension– Bugs can walk on it

Hydrogen Bonds

Cohesion

• Attraction between molecules of the same substance

• When like substances stick together– Water to water

Adhesion

• Attraction between molecules of different substances

• When different substance stick together• Ex- Glass and water- meniscus• Causes some things to get wet

Capillary Action

• Water moving up through a small tube• Adhesion- allows the water to stick to the

sides of the tube• Cohesion- allows the water molecules to stick

together while climbing– Ex: girls going to the bathroom as a group!!– Ex: water going up a plant from the roots

Capillary Action

Heat Capacity • Because of the multiple hydrogen bonds

water requires a lot of energy to heat up• Regulates temperature in

• Ocean and lakes• Cells

• Boiling water• How long does it take?• When can you touch it?

Mixtures

• Material composed of two or more elements or compounds that are physically mixed together but not chemically combined

• Two types that involve water– Solutions– Suspensions

Solutions

• Solute- what is being dissolved (Koolaid powder)

• Solvent- what the solute is being dissolved in (water)

• Solute + Solvent = Solution (Koolaid)

Water as a Solvent

• Water is the universal solvent• Because it is polar it can dissolve

– Other polar substances– Ionic compounds– Salts– Sugars– Minerals– Gases– Even other solvents such as alcohol

Water as a Solvent

• Saturated Solution- the water can’t dissolve any more solute

Suspension

• A mixture of water and non-dissolved material

• Some materials do not dissolve when placed in water, but separate into pieces so small that they do not settle out– Ex: blood

pH Scale

• pH stands for potential hydrogen, 0-14

pH Scale

• Measure the concentration of H+ (hydrogen ions)

• Above 7 is basic• 7 is neutral• Below 7 is acidic

Neutral

• Has equal numbers of H+ and OH-

• Ex: water

Basic

• A base is a compound that produces hydroxide (OH–) ions in solution.

• Ex: baking soda• Has more OH- than H+

• The closer to 14 the stronger• The closer to 7 the weaker• Usually end in -OH

Acids

• An acid is any compound that forms H+ ions in solution.

• Ex: orange juice, HCl (stomach acid)• Has more H+ than OH-

• The closer to 0 the stronger• The closer to 7 the weaker• Usually begin with H-

Buffers

• Keep solutions from becoming two acidic or basic

• Weak acids or bases• Essential in maintaining homeostasis• The pH of the fluids within most cells in the

human body must generally be kept between 6.5 and 7.5

Buffers

Carbon

• Has 4 valence electrons• Forms covalent bonds• Makes up organic compounds• Can bond with

• Hydrogen• Oxygen• Phosphorus • Sulfur• Nitrogen

Carbon

• Can bond to each other – Single – Double– Triple

Macromolecules

• Giant molecules• Made from monomers (single unit)• Polymer- many monomers

Organic Macromolecules

• Carbohydrates• Lipids• Proteins• Nucleic Acids

Carbohydrates• Organic compounds made of carbon, hydrogen

and oxygen in a proportion of 1:2:1• The building blocks of carbohydrates are called

monosaccharides• Glucose is a major source of energy for cells• Give an example of a food that contains

carbohydrates: pasta, bread, potatoes• Structural in plants- cellulose

Carbohydrates

• Sugars• End in –ose• Plants store energy

– starches

Carbohydrates

• Monosaccharide- Single sugar– Glucose, galactose, fructose

• Disaccharide- two sugars, table sugar• Polysaccharide- many sugars, glycogen

Lipids

• Important part of the structure and functioning of cell membranes

• Examples of lipids: waxes, fats, steroids, oils• Lipids that store energy are called fat• Give an example of a food that is a lipid: butter• Natural waterproofing

Saturated vs Unsaturated

Saturated vs. Unsaturated

• Saturated– Normally animal based– Solid at room temperature– No double bonds between carbons– Ex- butter

• Unsaturated– Normally plant based– Liquid at room temperature– At least one double bond between carbons– Ex- corn oil

Proteins

• Made of nitrogen, hydrogen, carbon, and oxygen

• Polymers made of monomers called amino acids• 20 amino acids• Peptide bonds link these monomers (type of

covalent bond)• Give an example of a food high in protein: meat,

fish, eggs, nuts

Functions of Proteins

• Enzymes - control the rate of reactions and regulating cell processes

• Forming cellular structures• Transporting substances into or out of cells,• Helping to fight disease.• Where is it found? Skin, bones, ligaments,

tendons• The most abundant protein in your body is

collagen

Levels of Protein Organization

• Four levels– Primary- sequence of amino acids (polypeptide)– Secondary- folding or coiling of the polypeptide– Tertiary- 3-d arrangement of polypeptide– Quaternary- made up of more than one

polypeptide

Levels of Protein Organization

Nucleic Acids• Made up of nucleotides (monomers)• Each nucleotide has three parts:

– sugar– base– Phosphate group

• Joined by covalent bonds

Nucleic Acids• There are two nucleic acids :DNA and RNA• DNA consists of 2 strand(s)

• Sugar- deoxyribose• RNA consists of 1 strand(s)

• Sugar- ribose

Nucleic Acids

• Store and transmit genetic information• Made of hydrogen, oxygen, nitrogen,

carbon, and phosphorus

ATP

• Carries energy for cells• When food is broken down some of the energy

in the molecules is stored temporarily in ATP

Energy

• Organisms need energy for life processes• Forms of energy

– Light, heat, electrical, mechanical, chemical• Energy can be absorbed or released by

chemical reactions– Reactions that release energy can occur

spontaneously (burning)

Chemical Reactions

• Process that changes, or transforms, one set of chemicals into another by changing the chemical bonds that join atoms in compounds

• Reactants- elements or compounds that enter into a chemical reaction

• Products- elements or compounds produced by a chemical reaction

Chemical reactions absorb or release energy

• If bonds are formed energy is absorbed• If bonds are broken energy is released• When water freezes heat energy is released• When ice melts heat energy is absorbed• When food is digested chemical reactions

convert chemical energy into a form cells can use

Energy Sources

• Animals- eat food• Plants- photosynthesis, sunlight

Energy is needed to start a chemical reaction

• The energy needed to start a chemical reaction is called activation energy

• Activation energy is like a chemical “ push” • Is activation energy needed in a reaction that

releases energy? Yes!

Catalyst

• Some chemical reactions are too slow or have activation energies that are too high to make them practical for living tissue

• Substance that speeds up the rate of a chemical reaction– Work by lowering a reaction’s activation

energy

Enzymes help reactions occur

• Natural catalysts• Enzymes increase the speed of chemical

reactions• Most enzymes are proteins• Enzymes are catalysts that reduce the activation

energy required to start a chemical reaction• Enzymes help organisms maintain homeostasis• Named for the reaction it catalyzes • Ends in -ase

Effect of Enzymes

Enzymes affect specific substances

• Enzymes act only on specific substrates• This is because only that substrate fits

into its active site• List the three steps of enzyme action:

1) Enzymes attaches to substrate at active site2) The enzyme changes the shape of the

substrate reducing the activation energy needed to start the reaction

3) The enzymes detaches from the substrate

Factors that affect enzyme activity

• Any factor that changes an enzyme’s shape will affect its activity

• List two of these factors:1) pH2) temperature

• Enzymes in the human body works best around 37 degrees Celsius