Chemistry Midterm Flashcards
Dimensional Analysis
Given Unit * (Desired Unit/Given Unit)
Precision
how close a series of measurements are to each other
Accuracy
how close a value is to an accepted value
Graduated Cylinder
used to measure volumes of liquids
Sig-Fig Rules
All non- zero numbers are always significant
Captive zeroes (between non zero numbers) are significant
If a decimal point is present, trailing zeros are significant
If a decimal point is not present, trailing zeros are not significant
Leading zeros are not significant
Adding and Subtracting Sig Figs
least precise measurement
Multiplying and Dividing Sig Figs
Fewest significant figures
Elements
cannot be further broken down through chemical means
Smallest particle of an element
an Atom
Compounds
chemically combined elements
Diatomic Elements
can only exist paired or in a compound — HONClBrIF
Monatomic Elements
group 18, noble gases
homogeneous mixture
uniform throughout
heterogenous mixture
is not uniform throughout
suspension mixture
heterogenous; particles that don’t dissolve, settle over time, seen through a microscope
colloid mixture
heterogeneous; stay suspended throughout the mixture, too small to settle
Seperation of Mixtures
Filteration - particle size
Distillation - boiling points
Separatory Funnel
Chromatography
Cathode Ray Tubes
Pass electricity through a gas that is contained at a very low pressure
Bohr Model
PEL #1 lowest in energy, closest to nucleus
PEL #7 highest in energy, farthest from nucleus
Lower energy levels are preferred by nature
Excited State
when electrons absorb energy
Ground State
electrons prefer lower energy, so they release energy in amounts called quanta.
orbitals
each PEL is divided into up to 4 sublevels: s, p, d, and f. within each sublevel there are orbitals ; regions in which electrons are most likely to be found
how do electrons fill orbitals
lowest energy (ground state) to highest energy. no pairs are put together unless necessary. no two electrons can ever be in the same place at the same time
hybridization
elements can rearrange their electron configurations
ion
an atom once it has gained or lost an electron; cation, anion
first ionization energy
energy needed to remove the outermost electron from a neutral atom
atomic number
of protons in the nucleus of each atom of an element; identification tag
Atomic Mass Unit
Mass of atoms
Isotopes
Same element, different mass
nucleons
protons and neutrons located in atoms nucleus
proton
positive charge, mass of 1 amu
neutron
no charge, mass of 1 amu
electrons
small, negatively charged subatomic particles in electron cloud, mass of 1/1836 amu
mass number
number of protons plus neutrons in nucleus of an atom
atomic mass
weighted average of all naturally occurring isotopes of an element
vertical columns
groups/families
horizontal rows
periods, same valuence electrons, same number of occupied PEL’s
metals
solid at room temp (except mercury)
shiny
malleable
ductile
good conductors of heat/electricity
low first ionization energies and low electronegativities
lose electrons to form cations
transition metals
3-12
hard solids, high melting points
form colored compounds
can form multiple possible positively charged ions
metalloids (semi-metals)
located along staircase
semi-conductors
partially ionic, partially covalent
silicon
non-metals
right, not including group 18
gases, molecular or network solids
brittle, dull
high first ionization energies and electronegativities
gain electrons, form negative ions
noble gases
group 18
non-reative (inert) bc completely filled outer valence shell
dont form compounds unless under extreme temp/pressure
allotropes
non-metals that exist in two more forms in the same phase;
different physical properties and chemical properties
- oxygen gas and ozone gas
- graphite, diamond
