H Chemistry: Unit 3 Flashcards
Democritus (400 B.C.)
-matter is composed of empty space through which atoms move
-atoms are solid, indestructible, and indivisible
-different properties of matter are due to different types of atoms
-changes in matter result from changes in the groupings of atoms
-discredited by Aristotle
John Dalton (1800)
-all matter is composed of atoms
-all atoms of a given element are identical
-atoms cannot be created or divided
-atoms combine in simple whole numbers to form compounds
-atoms are rearranged in chemical reactions
-atoms are divisible into subatomic particles
-atoms of the same element can have slightly different masses
atom
smallest particle of an element that retains all the properties of the element
Irving Langmuir (1881)
-established the size of an atom
-american scientist
size of an atom
1 billionth of a meter in diameter
Sir William Crookes (1820)
invented the cathode ray
cathode ray
glass tube hooked to a vacuum pump that is hooked up to two different charged electrodes
cathode
negative
anode
positive
J.J. Thomson (1890s)
-performed experiments with the cathode ray tube using magnets and found the negatively charged particles to be smaller than the atom
-credited for discovering electrons
plum pudding atomic model
negatively charged electrons are distributed throughout positively charged matter; sphere
Robert Milikan (1909)
-calculated the actual charge of the electron
-determined the mass of the electron
mass of the electron
9.1 x 10 ^-28 g
Ernest Rutherford (1911)
-gold foil experiment
-credited for discovering the nucleus of the atom and the proton
-nuclear model
gold foil experiment
where a narrow beam of positively charged alpha particles pass through a thin piece of gold foil and were reflected on a zinc sulfide screen
James Chadwick (1932)
discovered the neutron and that it has mass equal to that of a proton
Niels Bohr (1920-1940)
-improved Rutherford’s model by placing electrons at specific energy levels
-Bohr’s model
atomic number
indicates the number of protons
proton
positively charged subatomic particle located in the nucleus
-identifies the atom
-not gained or lost naturally in the lab
electron
negatively charged subatomic particle that orbits the nucleus
-determines reactivity
-number is the same as number of protons if atom is neutral
ion
charged atom from the gain or loss of electrons
anion
negatively charged ion from the gain of electrons
cation
positively charged ion from the loss of electrons
atomic mass
indicates the number of protons and neutrons together
-units are amu
mass of a proton/neutron
1 amu
neutron
neutrally charged subatomic particle in the nucleus of an atom
-calculated by taking the atomic mass and subtracting the atomic number
why is the atomic mass not a whole number
1) the mass of the proton and neutron in different elements differ slightly
2) the atomic mass is an average of all the isotopes of the element and their frequency
isotope
atoms of the same element with different masses because they have different numbers of neutrons
amu
-atomic mass unit
-1/12 of C-12
electromagnetic radiation
all forms of energy that travels in waves
wave length
distance between two identical points on a wave; measured in meters or nanometeres
frequency
number of waves that pass through a given point in 1 second; measured in inverse seconds or s^-1 or Hertz(Hz)
amplitude
energy in wave initiation
all electromagnetic radiation travels at
the same speed; c= 3.0 x 10^8 m/s
wave length is inversely related to
frequency, as wave length increases, frequency decreases
electromagnetic spectrum
list of all types of electromagnetic radiation
electromagnetic spectrum in order
radiowaves, microwaves, infrared radiation, visible light, ultraviolet, x-rays, gamma rays
Max Planck
experimented with heating objects and cooling them, he noticed that heat/energy was absorbed and released in “chunks”
quantum
minimum amount of energy that can be absorbed or released by an atom
photon
packet of energy that carries a quantum
energy does not exist
between the units
energy equation
E=hv (Planck’s constant)(frequency)
Planck’s Constant
6.626 x 10 ^-34 Js
atomic emission spectrum
unique band of colors emitted from an element when heated
Albert Einstein
propose that light is both a particle and a wave
photoelectric effect
light at a certain frequency when shined upon a specific metal will emit photoelectrons(no matter the duration or intensity)
Heinsburg Uncertainty Principle
you cannot know both the velocity and the location of an electron at the same time
quantum numbers
used to determine the location of an electron in an atom
1 principle quantum number
-primary energy level
-positive number that corresponds to the period on the periodic table
-higher the n, the higher the energy(usually)
-not a distance
2 angular momentum quantum number(l)(energy sub level)
-shows the shape of the orbital
orbital
region where there is a strong likelihood of finding an electron
s orbital
spherical
p orbital
dumbell
d orbital
shape varies
f orbital
shape varies
3 magnetic quantum number(Ml)
reveals the spacial orientation of the orbital
4 spin quantum number(Ms)
reveals the spin of the electron
pauli exclusion principle
- No two electrons can have the same four quantum numbers
- No more than two electrons in an orbital
orbital diagram
illustration of electron configuration
- arrow represents an electron
orbital diagram- s orbital
1 box
orbital diagram- p orbital
3 boxes
orbital diagram- d orbital
5 boxes
orbital diagram- f orbital
7 boxes
Hund’s rule
electrons will occupy an empty orbital of the same energy level before pairing up to avoid repulsion
afbau diagram
orbital filing diagram
valence electron
electron in the highest energy that are directly involved in bonding
lewis dot diagram
illustration of valence electrons
