Monday, Aug. 29 Please copy and answer the questions on a sheet of paper. 1.What is the difference between an element and a compound?What is the difference between an element and a compound 2.What is the difference between an atom and a molecule?What is the difference between an atom and a molecule 3.What is the difference between a proton, a neutron, and an electron?What is the difference between a proton, a neutron, and an electron 4.Compare H 2 O and H 2 O 2 ?Compare H 2 O and H 2 O 2

Elements Pure substances Can’t be broken down chemically into simpler kinds of matter Fewer than 30 elements are essential to life processes

Can you guess the top 6 elements that make up over 90% of your body mass? CARBON (C) HYDROGEN (H) OXYGEN (O) NITROGEN (N) PHOSPHORUS (P) SULFUR (S) CHOPNS!!!

Compounds Elements are social – they typically like to bond with other elements…more on that later. A compound is the result of bonding. Example: H + H + O  H 2 O gas gas liquid! Proportions of each kind of atom are fixed.

Exit Slip Here is the chemical formula for glucose: C 6 H 12 O 6 How many different elements make up glucose? Name them. How many atoms of Nitrogen are in glucose?

Atom vs Molecule

WRITE THIS DOWN! ATOM Simplest particle of an element Properties of different kinds of atoms determine the structure and properties of the matter they compose Cannot be directly observed Made up of subatomic particles MOLECULE Simplest particle of a compound Smallest one is 2 atoms big (H2), largest one is ? The answer varies. Held together by BONDS. (more later!) Made up of atoms

Proton, Neutron, Electron = SUBATOMIC PARTICLES Proton = positive charge, large, found in nucleus Neutron = no charge (neutral), large, found in nucleus Electron = negative charge, very small, found whizzing about the nucleus in a cloud

What forces hold an atom together? Electrical force “strong force”

How many … in an atom of ….? Atomic number = number of protons AND the number of electrons Why? Atomic Mass = number of neutrons + protons

Practice… 11 Na 23 An atom of sodium would have _________ protons _________ electrons _________ neutrons

Numbers matter If the number of protons changes….you have a different element! If the number of electrons changes…you have an ION! Ions conduct electricity… If the number of neutrons changes…you have an ISOTOPE! And that isotope could be RADIOACTIVE!!!

H 2 O vs H 2 O 2 Similarities: Both are chemical formulas Both are molecules They both contain hydrogen and oxygen Differences: H 2 O = water, 2 hydrogens and 1 oxygen H 2 O 2 = hydrogen peroxide, 2 hydrogens and 2 oxygens

So what?

Exit Slip: Minkonium 76 Mk 2011 What is the element symbol? # of protons? Location inside atom? # of electrons? Location inside atom? # of neutrons? Location inside atom?

So…bonding… The result of chemical reactions… Atom attachments Covalent bonds vs Ionic Bonds Covalent bonds = share electrons Ionic Bonds = one gains electrons, the other loses electrons…