Matter
Chemistry is …the study of the composition, structure and properties of MATTER, the changes which matter undergoes and the energy that accompanies these changes.
EVERYTHING that is made of atoms! What is matter? EVERYTHING that is made of atoms! What is not matter? Energy: heat, light, sound. . .
Atom Neutral particles Consists of subatomic particles Protons, neutrons & electrons
2 Categories of Matter Substance Mixture Element Collection of the same type of atom Cannot be decomposed Compound 2 or more different atoms chemically bonded together. Physical combination elements and/or compounds or both. USUALLY heterogeneous
Elements are represented with symbols DIATOMIC Elements The simplest form of these elements is a pair of atoms Go to 7 and make a 7. Don’t forget Hydrogen!
Characteristics of a Compound Individual atoms lose their original properties after bonding Composition is fixed can be decomposed / broken down
Compound vs. Molecule Molecule: applies only to bonded non-metal atoms
H2O O2 CO2 C6H12O6 NaCl Which are molecules? Which are compounds?
H2O O2 CO2 C6H12O6 NaCl Molecule & compound Molecule ONLY IONIC compound
Element? Compound? Mixture? Substance?
Answer: Mixture of elements
Element? Compound? Mixture? Substance?
Answer: Compound and Substance
?
Ans: mixture of compounds
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Substance and element
SOLUTION NaCl(s) + H2O(l) NaCl(aq) Only mixture that is homogeneous solute solvent aqueous solution Other solutions include Air (mixture of gases: N2, O2, CO2) & Alloys (mixture of metals: steel, brass & bronze)
Physical vs. Chemical
Physical Properties & Changes determined without changing the chemical composition of the substance Examples…. Color, shape, odor, malleability, brittleness, does it conduct electricity, does it conduct heat? state of matter (s), (l), (g) Melting point, boiling point… mass volume density D = m/v
…and absorption angular momentum area capacitance concentration dielectric ductility distribution efficacy elasticity electric charge electrical impedance fluidity frequency inductance Intrinsic impedance Intensity irradiance length location luminance luminescence luster magnetic field magnetic flux momentum opacity permeability permittivity plasticity radiance resistivity reflectivity refractive index spin solubility specific heat strength temperature tension viscosity
Can be intensive or extensive DON’T depend on sample size useful in identifying substances Ex. density DO depend on sample size volume weight mass
Chemical Properties determined during a chemical reaction with another substance Ex. Is it toxic, is it flammable, does it rust, does it tarnish, does it corrode…?
Chemical Change/ Chemical Reaction Results in the rearrangement of atoms to form a new substance BUT!!! We can’t see atoms so how do we know a chemical reaction has taken place?
The End