Chem-121 Exam
What is chemistry?
composition of matter, structure of matter, properties of matter, transformation of matter
What is chemistry (behaves)?
the way atoms, molecules, and electrons behave
What are atoms made of?
protons (positive)
neutrons (neutral)
electrons (negative)
What is the nucleus made of? What is it?
protons and neutrons
(incredibly dense and small)
Macroscopic?
"large"
humans can see and touch it
Microscopic?
"small"
visible through microscope/instruments
Symbolic?
using microscopic components to explain macroscopic
(eg. graphs, drawings, calculations, periodic table)
What is matter?
a substance made up of various types of particles that occupies physical space and has inertia
What is a solution?
a uniform liquid
What is a pure substance?
constant composition with same properties
(eg. sucrose (same melting pt, colour, and sweetness)
elements vs. compounds
element - can't be broken down (eg. gold, iron, and silver)
compound - can be broken into elements, compounds, or both (Mercury (II) Oxide when heated)
Heterogeneous vs Homogenous?
Heterogeneous - composition that varies from point to point (eg. chocolate chip cookies)
Homogeneous - uniform composition (eg. gatorade)
chemical properties vs. physical properties
chemical - one type of atom into another (eg. flammability)
physical - no change in chemical composition (eg. density, colour, and hardness)
What makes one type of atom different than another?
proton number
Is every atom of an element the exact same?
no
a charge arises from unequal #'s of protons (+) and electrons (-)
Atomic # and mass #?
atomic # - the number at the top
mass # - weight number
Is every atom of an element exactly the same?
No.
Two atoms of the same element and in the same electronic state could be traveling or rotating at different speeds, which affects their ability to chemically bond.
What is an ion?
- an atom or group of atoms
- carries a positive or negative electric charge as a result of having lost or gained one or more electrons
What is an isotope?
Atoms that have the same atomic number (number of protons), but different mass numbers
What is isotope abundance?
- the relative proportions of the stable isotopes of each element
What is mass spectrometry?
measures the relative masses of isotopes and their relative abundances
Weighted average?
molar mass thats equivalent to atomic mass
Atomic weight?
natural abundance/100*(isotopic mass)
= answer in amu
Avagadro's Constant
6.022*10^23