Unit 2 - Found or Forgery?

Dr. Johnson

electromagnetic radiation

forms of energy such as visible light, microwaves radio waves, infrared, ultraviolet light, and x-rays that travel as waves at the speed of light

crest

highest point on a wave

through

lowest point on a wave

wavelength (λ)

the distance between adjacent crests or troughs in a wave

frequency (v)

the number of times the crests of a wave pass a point in 1s

electromagnetic spectrum

the arrangement of types of radiation from long wavelengths to short wavelengths

inverse relationship

as the wavelength decreases, the frequency increases

as the wavelength increases, the frequency decreases

radio waves

radiation with long wavelengths used for AM and FM radiobands, cellular phones, and TV signals

microwaves

shorter wavelengths and higher frequencies than radio waves

Infrared radiation (IR)

responsible for heat felt from sunlight and infrared lamps uesd to warm food in restaurants

visible light

wavelengths from 700 to 400nm

only radiation our eyes can detect

ultraviolet (uv) light

shorter wavelengths and higher frequencies than violet light of the visible range

chemical symbols

an abbreviation that represents the name of an element

periodic table

an arrangement of elements by increasing atomic number such that elements having similar chemical behavior are grouped in vertical columns

group

a vertical column in the periodic table that contains elements having similar physical and chemical properties

group number

a number that appears at the top of each vertical column (group) in the periodic table and indicated the number of electrons in the outmost energy level

representative element

an element in the first two columns on the left of the periodic table and the last six columns on the right that has a group number of 1A through 8A or 1, 2, and 13 through 18

transition element

an element in the center of the periodic table that’s designated with the letter “B” or the group number of 3 through 12

period

a horizontal row of elements in the periodic table

alkali metals

an element in Group 1A (1), except hydrogen. this is a soft, shiny metal with one electron in its outermost energy level

alkaline earth metals

an element in Group 2A (2) that has two electrons in its outermost energy level

halogens

An element in Group 7A (17) that has seven electrons in its outermost energy level

noble gases

an element in Group 8A (18)

metals

an element that is shiny, malleable, ductile, and a good conductor of heat and electricity

the metals are located to the left of the heavy zigzag line on the periodic table

nonmetal

an element with little or no luster that is a poor conductor of heat and electricity

the nonmetals are located to the right of the heavy zigzag line on the periodic table

metalloid

an element with properties of both metals and nonmetals located along the heavy zigzag line on the periodic table

Dalton’s Atomic Theory

1. Matter is composed of tiny particles called atoms.

2. Atoms of given element are same and different from atoms of other elements.

3. Atoms of two or more different elements combine to form compounds. Particular compound is always made up of same kinds of atoms and always has same number of each kind of atom.

4. Chemical reaction involves rearrangement, separation, or combination of atoms. Atoms are neither created nor destroyed during chemical reaction.

subatomic particles

a particle within an atom; protons, neutrons and electrons are subatomic particles

electrons

a negatively charged subatomic particle having a minute mass that is usually ignored in mass calculations; its symbol is e-

protons

a positively charged subatomic particle having a mass of about 1 amu and found in the nucleus of an atom its symbol is p or p+

cathode ray tube experiment

plum pudding model

nucleus

the compact, extremely dense center of an atom, containing the protons and neutrons of the atom

neutron

a neutral subatomic particle having a mass of about 1 amu and found in the nucleus of an atom; its symbol is n or n0

atomic mass unit (amu)

a small mass united used to describe the mass of extremely small particles such as atoms and subatomic particles; 1 amu is equal to 1/12 the mass of a c512 atom

photon

a packet of energy that has both particle and wave characteristics and travels at the speed of light

atomic spectrum

a series of lines specific for each elements produced by photons emitted by electrons dropping to lower energy levels

energy level

a group of electrons with a similar energy

principal quantum number (n)

the energy of an electron can only have specific energy values, but cannot have values between these values

quantized

the energy of an electron can only have specific energy values, but cannot have values between these values

atomic number

a number that is equal to the number of protons in an atom

mass number

the total numbre of protons and neutrons in the nucleus of an atom

isotopes

an atom that differs only in mass number from another atom of the same element

isotopes have the same atomic number (number of protons) but different numbers of neutrons

ions

an atom with a net charge

atomic symbol

an abbreviation used to indicate the mass umber and atomic number of an isotope

Greeks (BCE) contribution to Atomic Theory

the idea athat all substances can be broken down into a tiny indivisible part

John Dalton’s (1803) contribution to the Atomic Theory

atoms of different elements have different masses and chemical properties

combine to make compounds

cannot be created or destroyed

JJ Thomson’s (1897) contribution to Atomic Theory

the idea that the atom is a positively charged mass with negative charges floating throughout (AKA Plum Pudding Model)

Cathode Ray Beam experiment

Ernest Rutherford’s (1911) contribution to Atomic Theory

the atom is a mostly open space with a postively charged nucleus in the middle

alpha particles shot at thin gold foil

Niel Bohr’s (1913) contribution to Atomic Theory

electrons orbited the nucleus with specific energy levels

planck’s constant

Quantum Mechanical Model (Schrodinger, Heisenberg, de Broglie [1920s])

electrons do not orbit, instead they float in the electron cloud