Reminders Unit 2 Exam- Monday 9/19 Unit 1 Retake: Thursday, September 15th during ASP Unit 2 Exam- Monday 9/19 Last day to turn in ANY Unit 2 Work- Monday 9/19 Assignments turned in for Unit 2: None yet!

Unit 2: Biochemistry 2.1 Structure of an Atom

The Atom The smallest particle of an element that retains the properties of the element World Population: 6 000 000 000 Atoms in a penny: 29 000 000 000 000 000 000 000

Relative electrical charge Particles that make up an atom Particle Symbol Location Relative electrical charge Relative Mass Actual mass (g) Proton p+ In the nucleus 1+ 1 1.673 x 10-24 Neutron N0 Electron e- In the space surrounding the nucleus -1 1/1840 9.11 x 10-28

Valence Electrons Valence electrons are the furthest from the nucleus and are responsible for bonding between atoms.

The Structure of an Atom Draw an atom in your notes. Be sure to label Protons, Electrons, Neutrons, and the Nucleus.

Element Element: A substance that cannot be broken down into simpler substances Ex- gold, copper, oxygen 92 occur naturally, 20+ are man-made

Compound Compound: A substance that has 2 or more elements in a fixed ratio Ex- Salt (NaCl)- made from a silvery metal and a greenish-yellow, poisonous gas Neither are white or salty alone Fixed composition… 1 Na, 1 Cl + =

Question? What Elements are necessary For Life? Life requires about 25 chemical elements.

Energy The ability to do work.

Potential Energy Is the energy that matter stores because of its position or location. Electrons have potential energy because of their position relative to the nucleus.