Chapter 4 Quiz Flashcards
What were the flaws in Democritus’ theory?
Did not explain chemical behavior
Was not based in the scientific method
Was not supported by experimental data
What was Democritus’ theory?
First suggested the existence of atoms.
Atoms are indestructible and indivisible.
What did John Dalton’s Atomic Theory state?
Elements are made of indivisible particles called atoms
Atoms of the same element are identical
Different atoms can form mixtures of compounds
Chemical reactions arrange atoms in different combinations but can’t change an atom into a different atom
How can we observe the atom?
Scanning electron microscopes
What did Dalton’s theory not explain?
What atoms are made of
What does an electric generator do? What are the components used to create an electric current?
An electric generator creates an electrical output.
Mechanical energy + magnets + wire = electric current
What is an electric current?
Stream of electrons moving in one direction
Who discovered the electron? What was his experiment and its components?
J. J. Thomson
Cathode Ray experiment:
Filled a tube with gas and fitted it at each end with metal disks called electrodes. The electrodes were connected to a source of electricity. A bright source of light appeared.
NEGATIVE= Cathode POSITIVE= Anode
What did Thomson name the electron?
Corpuscles
What was Robert A. Millikan’s experiment? What did he find out?
Oil droplet experiment:
Suspended negatively charged oil droplets between two charged plates, changing the voltage on the plates to see how it would affect their fall.
Discovered the charge of one electron to be 1.60 x 10^-19 coulomb.
Millikan calculated am electron’s mass through Thomson’s charge-to-mass ratio.
What did Eugen Goldstein suggest?
Atoms are comprised of protons (positively charged subatomic particles).
Studied a cathode ray
Who confirmed the existence of the Neutron?
James Chadwick
Who made the Plum Pudding Model?
J. J. Thomson
What was Rutherford’s experiment and what did he learn?
Gold Foil experiment:
Tested to see if a beam of positively charged alpha particles would go directly through a piece of gold foil. It SHOULD have passed through because the atom was thought to be soft.
Learned that the atom is mostly empty space
Something small, hard, and positively charged in the atoms.
What was Rutherford’s atomic model called?
Nuclear atomic model
What makes atoms of different elements so different?
Different number of protons (ATOMIC NUMBER)
What is the mass number?
Total number of protons and neutrons.
What is the subscript?
BELOW
Atomic number
What is the superscript?
ABOVE
Mass number
What is an isotope?
Atoms that have the same number of protons but different numbers of neutrons
How is the amu defined?
One Twelfth of the mass of a Carbon-12 Atom
1 Proton = 1 Amu
1 Neutron = 1 Amu
What is atomic mass?
A weighted average mass of the atoms in a naturally occurring sample of the element
Mass and relative abundance
What is atomic mass measured in?
AMU
What is the atomic number?
The number of protons in the nucleus of an atom
