Scientists
Describe the first model of the atom postulated by Dalton. Then explain why this model is no longer valid.
What is : the cannonball model, a small hard indivisible sphere. No longer valid because subatomic particles were discovered.
Determines the identity of an element.
What is the number of protons, or atomic number?
Define the term ion.
What is an atom with a net charge, or an atom that has unequal numbers of protons and electrons?
List the charge and mass of each subatomic particle.
What is ...
proton - positive charge and 1 amu
neutron - neutral charge and 1 amu
electron - negative charge and 1/1836 amu
The weighted average mass of all of an element's isotopes.
What is the average atomic mass?
Particle found in the rings in the Bohr diagram.
What are electrons?
What structure did Rutherford discover was in an atom after his gold foil experiment?
What is a nucleus?
A (n) _____ is a very small particle that is the basic unit of matter.
What is an Atom?
Explain what happens when excited electrons fall back to their ground state.
What is emit energy/light and jump to the lowest energy configuration?
The most dense structure in an atom called _______ is made up of ______ and ______.
What is : nucleus; protons and neutrons?
The number of protons in an atom of an element is its
What is atomic number?
Draw a Bohr model of Boron.
What is 2 electrons in the first shell and 3 electrons in the second shell?
Particle discovered by J.J. Thomson??
What is the electron?
Isotopes of the same element have the same number of protons but different number of _________
What is neutrons?
The current atomic theory includes the ________ model of electrons.
What is the electron cloud?
How many electrons can fit in the first, second, and third shell?
What is 2, 8, 18?
Describe the difference between atomic number and mass number.
What is : The Atomic Number is the number of protons in an atom. The Mass Number is the sum of the number of protons and neutrons in an atom of a particular isotope.
Number of "shells" or "rings" in an oxygen atom based on the Bohr model. Then, number of electrons found in the outermost shell.
What is 2 shells and 6 electrons in outermost shell?
Experiment that led to Thomson's plum-pudding model of the atom.
What is the Cathode Ray Tube experiment?
In an atom, which has the least mass? A: nucleus B: proton C: neutron D: electron
What is : electron
Explain how an electron becomes 'excited".
What is the electron absorbs energy and jumps to a higher energy level (orbital)?
The probable location of an electron.
What is the electron cloud or orbital?
What is the lowest possible energy configuration for the electrons. For representative elements, lowest shells fill first.
Compare Bohr models and Lewis dot models.
What is Bohr models include the electrons in each orbital, Lewis dot only includes valence shell electrons?
Explain the difference between Bohr's orbital model and the modern wave mechanical model.
What is Bohr's models shows electrons in orbits about the nucleus like planets, while the modern model shows the electrons in a cloud based on probable location?
Two subatomic particles that determine the atom's mass.
What are Protons and Neutrons? Electrons are too light (relatively) to count towards the atomic mass.
Define valence electron.
What is an electron that is found in the outermost occupied energy level?
Two particles that determine the net charge of an atom.
What are protons and electrons?
The atomic mass unit is based on what element.
What is Carbon-12? That is, Carbon is used as the standard to define that each proton and neutron has a relative mass of 1 amu.
Draw the Lewis dot diagram for bromine and bromide ion.
What is Br and Br 1-?