The Chemical Basis of Life Chapter 4 The Chemical Basis of Life

Matter All living things are made up of matter – anything that has mass and takes up space Water, air, and your body are different substances but are all made up of matter

NOT IN PACKET MATTER – solid, liquid, gas, plasma MOLECULES ATOMS SUBATOMIC PARTICLES Protons Electrons Neutrons

Mass – the amount of matter an object has Mass vs Weight Mass – the amount of matter an object has Weight – the amount of mass an object has plus the force of gravity

Matter exists in 4 different states Solid – definite shape and volume States of Matter Matter exists in 4 different states Solid – definite shape and volume

Liquid – definite volume, not shape Gas – no definite shape or volume

Plasma - high temperature ionized gas

Elements Element – substance made up of the same type of atoms that can not be broken down chemically into a simpler kind of matter

25 elements are important to living things 4 make up 96% of the living matter in your body Oxygen, Carbon, Hydrogen, Nitrogen

Trace elements – elements that make up less than Trace elements – elements that make up less than .01 percent of body mass, but critical to health Ex. 1.5 mg of Iodine each day – affects thyroid gland .004% Iron – important for O2 in your blood

Compounds Compound – substance containing 2 or more elements that are chemically combined in a fixed ratio Ex. H2O

Physical and chemical properties differ between the elements that make up the compound and the compound itself Ex. Oxygen and Hydrogen = gases Combined = liquid

Atom – smallest possible particle of an element Greek atoms = invisible Nucleus – consists of protons and neutrons and makes up most of the mass of the atom

Proton – positively charged particle Neutron – neutral; particle with no charge Electron – high energy, negatively charged particle with little mass

Each orbit holds a certain amount of electrons Atoms Orbital – 3D region around a nucleus that indicates the probable location of an electron Each orbit holds a certain amount of electrons

1st orbit – 2 e 2nd orbit – 8 e 3rd orbit – 8 e

Ex. He and Ne both have 8 e in their outer orbits Atoms In order to be stable, an atom must have its outer orbit filled with electrons Ex. He and Ne both have 8 e in their outer orbits

Atoms have the same number of protons (+) as electrons (-), therefore, an atom is neutral

Periodic Table – chart that summarizes and organizes the elements Atoms Periodic Table – chart that summarizes and organizes the elements Chemical symbol – letters

Atomic number – number of protons an atom has Mass number – total number of protons + neutrons Ex: F 9 protons 10 neutrons = 19 atomic mass

Isotopes Isotopes – atoms of the same element that have the same number of protons, but different number of neutrons

Radioactive Isotope – one in which the nucleus decays over time, giving off radiation in the form of matter and energy Used in research and in medicine

Ionic Bonds Ionic bond – the attractive force between oppositely charged ions which form when electrons are transferred from one atom to another

Ion – electrically charged atom or molecule Ex. NaCl

Ex. Water Oxygen 6 electrons needs two Hydrogen Covalent Bonding Covalent bond – forms when two atoms share one or more pairs of electrons Ex. Water Oxygen 6 electrons needs two Hydrogen

Molecule – 2 or more atoms held together by a covalent bond Molecules Molecule – 2 or more atoms held together by a covalent bond Ex. H20 or O2

Chemical formula - #’s and types of atoms Models of Molecules Chemical formula - #’s and types of atoms Structural formula – how the atoms are linked by bonds Space filling model – 3-D model with colored spheres

Reactants – starting materials for a rxn Chemical Reactions Chemical Reactions – breaking of old and formation of new chemical bonds resulting in a new substance Reactants – starting materials for a rxn Products – ending materials in a rxn

Hydroxide ion = OH- Hydronium ion = H+ Acids, Bases, and pH H2O H+ + OH- Hydroxide ion = OH- Hydronium ion = H+

Acid – solution with more H+ Ex. HCl Base – solution with more OH- Ex. NaOH

pH Scale pH scale – scale range from 0-14 that describes how acidic or basic a solution is 0-6 acid 7 neutral 8-14 base

Buffer – substances that cause a solution to resist changes in pH Important because the slightest change in pH can be harmful to organisms Ex. Blood

On the back of your paper write: Acids Neutral Base