Building a “Cereal” Atom

Two Minutes… http://timer.onlineclock.net/ What do you already know about atoms?

Atoms Building blocks of matter What is matter? Atoms are made up of subatomic particles: protons, neutrons, & electrons. Atoms have a dense, heavy nucleus surrounded by electron shells.

Subatomic Particles Protons Have a positive charge Located in the nucleus Weigh 1 amu (atomic mass unit)

Subatomic Particles Neutrons Are neutral with a charge of 0 Located in the nucleus Weigh 1 amu

Subatomic Particles Electrons Have a negative charge (1 e = -1) Located in an electron cloud surrounding the nucleus Electron cloud is actually made up of energy levels Weigh 5.5 x10-4 amu = .00055 amu

Electron Energy Levels Level 1 holds 2 e- Level 2 holds 8 e- Level 3 holds 18 e- Level 4 holds 32 e- Draw a picture on your notes!

Create a Cereal Atom 2 minutes… http://timer.onlineclock.net/

Element Pure substance that can’t be broken down into any other substances physically or chemically Made up of only one type of atom Each element has a specific, unique atomic number, name, and symbol Carbon’s atomic number is always 6 and no other element can have this number! Symbol for Carbon = C

Atomic Number (Z) Number of protons in the nucleus of an atom Defines an element Each element has their own atomic number

Mass Number (A) The total number of protons and neutrons in the nucleus of an atom Find the number of neutrons if you are told an element has an atomic number (Z) of 29 and a mass number (A) of 63? What is this element? Neutrons = A - Z

Build your atom! Choose an element with your partner and create an atom of that particular element with the correct number of p+, n, and e-. Place a notecard next to your atom with the element symbol, atomic number, and mass number.

Isotope Forms of the same element that have the same number of proton and electrons but a different number of neutrons This does not change the atom’s charge Ex: C12, C13, C14 are all Carbon isotopes

Valence Electrons Electrons found in the outermost electron shell of an atom The number of valence electrons can be determined by the columns on the periodic table *Let’s label our periodic tables! Valence electrons determine how (and whether) the atom will react with other atoms

Why are some atoms very reactive while others are more stable? Octet rule- atoms are more stable when their outer electron shells are full, thus some atoms will readily react to lose or gain electrons to fulfill the octet rule They are stable when they have the maximum number of valence electrons in their outer shell Examples: Helium, Sodium, & Fluorine

Atom Stability Atoms are most stable when their outmost energy level is completely filled If it is not, atoms can donate or accept electrons to fill their out energy level to become more stable Would Sodium (Na) want to donate or accept an electron? How about Calcium (Ca)?

Ion An atom that has lost of gained one or more electrons Has an electric charge A positive ion = cation A negative ion = anion

Sodium Ion

Ionic Bond Occurs when 2 oppositely charged ions attract each other and from a compound Example: NaCl (sodium chloride)

How does this relate to Carbon? Why doesn’t Carbon ever form ions? Carbon has 4 valence electrons, so it would take a lot of work to add 4 or lose 4 electrons Instead carbon shares 4 electrons with other atoms Covalent bond- when 2 atoms share electrons

All living things are made up of carbon! What is the importance of Carbon’s stability in biological systems? Carbon can bond with other atoms in a large number of different ways, making a huge variety of large complex molecules that make up all living organisms Carbon mainly bonds to other carbon atoms, oxygen, hydrogen, and nitrogen