Elements, Compounds, and Chemical Changes

Separation ___________________ How can you separate these solutions?? Milk (proteins are suspended in solution) Blood (cells and proteins are suspended in solution) ___________________ Yields two layers (solution on top, suspensions on bottom)

Density Review: Mass- How much matter is contained in an object Volume- How much space an object takes up Density- ??

Density Derivation If density is the amount of matter per unit of volume, then what is the equation to calculate density? Equation  __________________________ How much space will a 54.8 g sample of Fe occupy if the density is 7.86 g/mL Note: g/mL = g/cm3 = g*mL-1 = g*cm3-1

Graphical Analysis Volume on the x-axis, Mass on the y-axis As the volume increases for a given substance, so does the mass, at a constant rate. The slope of this line is the DENSITY!! We can determine the identity of an unknown substance using its density.

Atoms are the Fundamental Components of Elements The Periodic Table contains a relatively small number of atoms that form an unlimited number of different materials. This is based on how they combine or bond together

Atoms are the Fundamental Components of Elements The Periodic Table contains a relatively small number of atoms that form an unlimited number of different materials. This is based on how they combine or bond together Element – Any material consisting of only one type of atom. Atom – Submicroscopic particles in a sample. Each element is designated by a symbol (Atomic Symbol) Co =/= CO, only the first letter is capital

Atoms are the Fundamental Components of Elements Elemental Formula – How many atoms are bonded together in an element Au = Gold ii. N2 = Nitrogen iii. Ni = Nickel Seven Diatomic Elements: Oxygen, Hydrogen, Nitrogen, Bromine, Chlorine, Iodine, Fluorine How about diatomic oxygen vs. ozone, O3? Are they the same? No, BUT both are elemental forms of oxygen

Combining Elements to Form Compounds Molecule- Consists of two or more atoms combined in a definite ratio Compound– Atoms of different elements bound to one another We had an Elemental Formula for elements, how will we represent chemicals bound together to form chemical compounds?

Combining Elements to Form Compounds We had an Elemental Formula for elements, how will we represent chemicals bound together to form chemical compounds? Chemical Formula – How much of what is in the compound (symbols and subscripts) NaCl: One sodium per chlorine atom MgCl2: One magnesium per two chlorine atoms

Combining Elements to Form Compounds Hydrogen Sulfide is one of the smelliest compounds. Rotten eggs get their characteristic bad smell from the hydrogen sulfide that they release. Can you infer from this information that elemental sulfur is just as smelly? *Compounds have Physical and Chemical properties that are different from the properties of their elemental compounds

Chemical Changes (rxn) Remember, a change is chemical ONLY when the BONDS are BROKEN and reformed. This process creates entirely new substances called ________________. This change is NOT physical because you CANNOT GO BACK!! 

Chemical Changes Compounds (several DIFFERENT elements together) can be broken down CHEMICALLY to their ELEMENTAL forms Elemental forms are those consisting of ONLY one type of element Ex: H2O  O2 + H2 (new elemental PRODUCTS were created)

Homework Page 47-48, #32, 33, 34, 35, 37, 44, 45, 46 Please do on a separate sheet and be ready to turn in for a grade (must have the assignment written on the top line and be neat!!)