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28 Cards in this Set

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how do you calculate percent composition?

percentage = part/whole x100%

how do you find the percentage of mass of a compound?

% element = (number of atoms)(atomic weight)/(FW of the compound) x 100

how do you calculate the empirical formula?

1. change % to grams


2. change grams to moles


3. divide by the mole amount


4. multiply each # by the same integer to get whole #'s (clear fraction)


5. write formula with the proper subscripts

Where are the protons location in the atom?

in the nucleus

Where is the mass/atomic number located in the writing of the complete atomic symbol?

top left side of the element

what is located at the bottom left side of the element in the complete atomic symbol?

number of atoms

what do you need in order to calculate the average atomic mass for an element?

atomic mass of different isotopes and relative abundance

what are chemical isotopes?

atoms with same number of protons but different number of neutrons

what the difference between a cation and an anion?

cation is positive and anion is negative

what are the 5 main points of dalton's atomic theory?

1. all matter is composed of very small particles called atoms


2. atoms of an element are identical in size, mass etc.


3. atoms cannot be subdivided, created or destroyed


4. atoms are different elements combined in simple, whole number ratios to form chemical compounds


5. in chemical reactions, atoms are combined, seperated or rearranged

what is an atom?

smallest particle of an element that retains the chemical properties of that element

what is an electron?

negatively charged particles surrounding the nucleus

what is a neutron?

neutral particles found in nucleus with protons

what is a proton

positively charged particle found in nucleus with neutrons

what is a nucleus?

small region located at center of atom with protons and neutrons inside

What did Thomson say about cathode rays?

cathode rays must be composed of identical negatively charged particles named electrons

What did Milkilan find?

found measure of charge of the electron

What did Rutherford find?

volume of nucleus was very small compared with total value of atom; deflected alpha particles experienced some powerful force within the atom

what is the atomic number?

(z) number of protons of each atom of an element

what is the mass number?

total number of protons and neutrons that make up the nucleus of the isotope

what is the relative atomic mass?

one atom chosen as standard and assigned a mass value. Masses of other atoms are expressed by this standard

What is the average atomic mass?

Weighted average of the atomic masses of the naturally occurring isotopes of an element

what is a mole?

(mol) amount of a substance that contains as many particles as there are atoms in exactly 12g of carbon

what is avagadro's number?

6.022 x 10^23

what is the molar mass?

mass of one mole of a pure substance

what is an isotope?

atoms of same element with different masses

what does the catharay experiment prove?

1. found the first subatomic particle discovered (negatively charged)


2. discovered the electron


3. smaller than hydrogen

What did the gold foil experiment prove?

1. atoms were largely empty space


2. occassionally hit something and came back (hit nucleus)


3. small positive charge (nucleus)