Advertisement Upgrade to remove ads

things that might be important from chapter 2

Democritus and early Greek philosophers

thought the material would must be made of tiny invisible particles called atomos meaning "indivisible or uncuttable"

Isaac Newton

favored the idea of atoms

John Dalton

created Dalton's atomic theory

Dalton's atomic theory-1

Each element is composed to extremely small particles called atoms

Dalton's atomic theory-2

All atoms of a given element are identical to one another in mass and other properties, but the atoms of one element are different from the atoms of all other elements.

Dalton's atomic theory-3

The atoms of one element cannot be changed into atoms of a different element by chemical reactions; atoms are neither created nor destroyed in chemical reactions

Dalton's atomic theory-4

Compounds are formed when atoms of more than one element combine; a given compound always has the same relative number and kind of atoms

atoms

smallest particles of an element that retain the chemical identity of the element

law of conservation of mass

The total mass of materials present after a chemical reaction is the same as the total mass present before the reaction.

law of multiple proportions

if two elements A and B combine to form more than one compound, the masses of B that can combine with a given mass of A are in the ratio of small whole numbers.

subatomic particles

the atom is composed of these smaller parts

particles with the same charge

repel one another

particles with unlike charges

attract one another

cathode rays

radiation produced from the negative electrode when high voltage was applied to partially excavated tubes

cathode

negative electrode

J. J. Thomson

observed cathode rays and discovered the electron, "plum-pudding model"

Robert Millikan

oil-drop experiment; discovered the mass of an electron

radioactivity

the spontaneous emission of radiation

Henri Becquerel

studying uranium and discovered it spontaneously emits radiation

Marie Curie

with husband began experiments to isolate radioactive components of uranium

Ernest Rutherford

revealed three types of radiation: alpha, beta, gamma; "gold foil experiment"

"plum-pudding model"

J. J. Thomson proposed that the atom was a uniform sphere with embedded electrons

protons

positively charged particles in the nucleus

neutrons

neutral particles in the nucleus

James Chadwick

discovered neutrons

electronic charge

1.602 x 10⁻¹⁹ C; all charges of subatomic particles are represented as multiples of this charge

atomic mass unit

1.66054 x 10⁻²⁴ g = 1 amu

angstrom

A°, 10⁻¹⁰ m

atomic number

the number of protons in any element (subscript)

number of electrons

same as number of protons

mass number

total number of protons plus neutrons in an atom (superscript)

isotopes

atoms with identical atomic numbers but different mass numbers

average atomic mass

found using masses of isotopes and relative abundance on earth

metallic elements or metals

left side and middle of periodic table

nonmetallic elements or nonmetals

separated from metals by a diagonal step ladder in the periodic table

metalloids

lie along the line between metals and nonmetals in the periodic table

molecule

assembly of two or more atoms tightly bound together

chemical formula

shows the elements in the compound and the ratio of atoms

diatomic molecule

made up of two atoms

molecular compounds

composed of molecules of more than one type of element

molecular formulas

actual numbers and types of atoms in a molecule

empirical formulas

lowest ratio of elements in a molecule

structural formula

shows which atoms are attached within a molecule

ion

a charged particle

anion

negatively charged particle

cation

positively charged particle

polyatomic ions

consist of atoms joined as in a molecule with a net charge

ionic compound

compound that contains both positively and negatively charged ions

chemical nomenclature

system for names and formulas of compounds

hydrocarbons

only contain carbon and hydrogen

alkanes

hydrocarbons that contain carbon atoms that are bonded to four other atoms

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again

Example:

Reload the page to try again!

Reload

Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording

Create Set