Chemistry of Life Honors Biology Chapter 2

Matter Anything that has mass and takes up space

Mass Quantity of matter an object has NOT weight: the amount of force produced by gravity acting on mass

Elements Substances that cannot be broken down chemically into simpler kinds of matter More than 100 types Organized on the periodic table of elements

Elements of Life Approximately 27 are essential to life 90% of mass of living things are O, C, H, N Elements of Life: CHONPS Remember the Elephants in the Element Song?

Atom Smallest unit of an element that retains all the properties of that element

Nucleus Central region of an atom Contains the bulk of the mass of the atom Consists of protons and neutrons

Proton Positively charged particle Located in Nucleus Mass approximately 1 AMU logo_ _m.jpg

Neutron Neutral charged particle, No Charge Located in Nucleus Mass approximately 1 AMU atom_e1.gif

Electron Negatively charged particle Orbits the nucleus in the electron cloud Mass practically zero

Orbitals Electrons orbit in specific regions called orbitals- 3D space higher probability location of orbital Each orbital is associated with an energy level Electrons in orbitals further from the nucleus have more energy

Electron Orbitals & Energy Levels Each orbital can hold 2 electrons Each energy level consists of different #s of orbitals

Build an Atom

Atomic Number Number of protons in an atom Determines type of element Elements are organized by atomic number on the periodic table Atomic Number for Carbon is 6

Mass Number Total number of Protons + Neutrons Protons have mass of 1 amu Neutrons have mass of 1 amu Mass Number – Atomic Number = # of neutrons g

Mass Number DFx20P3q3fw/TciZDNxjLQI/AAAAAAAAACU/BsGwZgYExOM/s1600/isotopes.jpg

Isotopes Atoms are stable with certain numbers of neutrons Atoms with different numbers of neutrons are called Isotopes

Build an Atom

Compounds Made of atoms of two or more elements in fixed proportions Chemical formula shows kinds and proportions of atoms H 2 O - C 6 H 12 O 6 – CO 2 - CO - O 2 - Compound?

Molecule Simplest part of a substance that retains all properties of that substance Can exist in a free state Can be very large- carbohydrates, lipids, proteins, nucleic acids (macromolecules) H 2 O - C 6 H 12 O 6 – CO 2 - CO - O 2 -

Chemical Bonds Attractive forces that hold atoms together Covalent Bonds Ionic Bonds Hydrogen Bonds Stable Atom = Highest energy level filled

Valence Electrons Number of electrons in the highest energy level for that atom Atoms are more stable when outer energy level is full (2 or 8 electrons depending on element)

Dot Diagrams Show the valence electrons on an atom Hydrogen and helium only hold up to 2 valence electrons Other elements (that we will look at) hold up to 8 valence electrons

Covalent Bond Two atoms share one or more pairs of electrons

Ion Some atoms only need to gain or lose 1 or 2 electrons to be stable Ions- Forms of an atom that have gained or lost electrons Fills the outer shell of electrons If electrons are gained, Ion is NEGATIVE (ANION) If electrons are lost, Ion is POSITIVE (CATION)

Ion Example Sodium and Chlorine

Ionic Bonding Atoms form ions and become positive or negative Opposite charges attract