This scientist believed that atoms were indivisible and indestructible.
Democritus
100
What are the three kinds of subatomic particles?
protons, neutrons, electrons
100
In a neutral atom, the atomic number also equals the number of ________________
Protons as well as electrons
100
Isotopes differ from other isotopes of the same element due to a change in what?
Neutrons
100
The horizontal row of the periodic table is called a ________________.
period
200
What was wrong with Democritus' idea of the atom?
It didn't explain chemical behavior and lacked experimental support.
200
What scientific instrument/tool helped us understand charges of particles?
cathode ray tube
200
Atomic mass is composed of what two particles in an atom?
protons and neutrons
200
Oxygen has 3 isotopes: carbon-16, carbon-17, and carbon-18.....the average atomic mass is 15.999amu. Which isotope is more abundant?
carbon-16
200
The vertical column of the periodic table is referred to as a _______________.
group or family
300
How did Dalton transform Democritus' ideas into a scientific theory?
He conducted experiments.
300
Where are electrons found?
around the nucleus/electron orbits
300
What makes on element different from another?
The number of protons OR atomic number.
300
Isotopes are chemically alike because they have identical numbers of _____________ and _____________.
protons and electrons
300
How do you determine the number of neutrons in an atom? What is the equation?
# of neutrons = atomic mass - # of protons OR # of neutrons = atomic mass - atomic #
400
Chemical reactions occur when atoms are ____________, _____________, or _______________.
separated, joined. or rearranged
400
What is the relative mass of a an electron?
1/1840 size of a proton
400
How many electrons does a neutral chlorine atom have?
17
# of electrons = # of protons = atomic #
400
Regarding the carbon-12 isotope, one atomic mass unit (amu) is defined as what fraction of the carbon-12 atom?
1/12
400
What scientist did the gold-foil experiment?
Ernest Rutherford
500
Individual atoms are observable with what?
Scanning tunneling microscope
500
Who discovered the electron?
J.J. Thomson
500
How many neutrons does a neutral fluorine atom have?
10
Atomic mass - atomic # = # of neutrons
19 - 9 = 10
500
The weighted average mass takes into consideration what two values for each isotope?
mass and relative abundance
500
Given the following information, what is the average atomic mass for nitrogen? You must show work!
**Round to the nearest .001
Nitrogen-14: 14.003amu, 99.63%
Nitrogen-15: 15.000amu, 0.37%
14.003 x .9963 = 13.9511889
15.000 x .0037 = 0.0555
13.9511889 + 0.0555 = 14.007 amu