Historical People
His atomic model might put you asleep, but it explains that electrons move between fixed shells that circle around the nucleus.
Niels Bohr's atomic model.
In which state does an atom have more energy, but is less stable
The excited state.
Which subatomic particle has mass, but no charge?
Neutron
It is neutral and has a mass close to that of the proton.
What are the rows and columns of the periodic table called?
Rows are called periods, and columns are called groups.
What law states that matter cannot be created or destroyed, but it can change forms?
Law of conservation of mass
Where are the positive charges in Rutherford's atomic model with a nucleus?
Positive charges are concentrated in the center of the atom.
What atomic model gets it's name from a weather-like formation, which represents all the orbitals in an atom?
An electron cloud.
This subatomic particle has a negative charge.
The electron.
The atomic number of an element also represents the number of what in that atom.
The number of protons.
The nuclei of isotopes contain different numbers of what?
Neutrons.
TRUE or FALSE
John Dalton's atomic theory mentioned how atoms were made of subatomic particles.
False. Ernest Rutherford discovered subatomic particles with his gold foil experiment.
An atom's lowest energy level has how many orbitals?
Only 1 orbital.
TRUE or FALSE
The number of protons is unique for each element.
True.
Which group of elements on the periodic table are the most reactive?
Group 1A elements, the alkali metals, are the most reactive. This is because they only have 1 valence electron.
What determines an element's chemical properties?
The number of valence electrons.
Who can we credit for developing the concept of the Periodic Table of Elements?
Dmitri Mendeleev
What two particles are located in the nucleus and add up to the atom's mass?
The proton and neutron.
How many electrons can an orbital contain?
Maximum of 2.
If an atom of gallium has a mass number of 68 and an atomic number of 31, how many neutrons are in its nucleus?
68-31=37 neutrons
Halogen's are located in group 7A. Which atom in Sodium Chloride (table salt) is halogen? Sodium (1 valence electron) or Chloride (7 valence electrons)?
Chloride is the halogen because it has 7 valence electrons.
Who was the first to argue that all matter was made from indivisible particles?
Democritus
He argued for atoms as the smallest unit of matter in 450 B.C.
Which atomic orbital has the least energy?
An electron has more energy in orbitals farther from the nucleus. So, the inner most orbital has the least energy.
The number of electrons in the orbitals equals the number of what in the nucleus?
The number of protons.
If Phosphorous has 15 protons and 16 neutrons in it's nucleus, how many electrons does is have?
What is it's atomic number and mass?
Atomic number = # Protons (15)
Atomic mass = Protons + Neutrons
15+6=31
Alkali metals are located in group 1A. Which atom in Sodium Chloride (table salt) is Alkali? Sodium (1 valence electron) or Chloride (7 valence electrons)?
Sodium is Alkali because it has 1 valence electron and those are in Group 1A.