Structured
Two more elements join together to form these.
What are compounds?
He theorized that electrons are arranged in energy levels, and if they absorb energy, they jump to the next level.
Who is Niels Bohr?
Scientists have not actually seen these smallest parts of an element.
What is an atom?
This Greek first proposed the idea of atoms.
Who is Democrius?
A neutral atom of oxygen has how many protons, electrons, and neutrons?
These have a positive charge and are located in the nucleus.
What are protons?
This law explains why chemical compounds always have a specific composition.
What is the law of constant composition?
This is the number of protons in an atom.
What is the atomic number?
He suggested that there must be a tiny but concentrated positively charged mass in the center of an atom.
Who is Rutherford?
The isotope Carbon-13 has how many protons, neutrons, and electrons?
These have a neutral charge and are located in the nucleus.
What are neutrons?
This law states that matter cannot be created or destroyed but changes from one form into another.
What is the law of conservation of matter?
This is the sum of protons and neutrons in the nucleus of the atom.
What is the mass number?
This model shows electrons spread evenly throughout the model.
What is Thomsom's plum pudding model?
If the mass number is 38 and there are 20 neutons, how many protons are in this atom?
What are 18 protons?
These have a negative charge, orbit the nucleus, and are the smallest of the three subatomic particles.
What are electrons?
This complex model illustrates that electrons do not follow set paths but rather orbit within a cloud.
What is the quantum mechanical model or the electron cloud model?
These electrons are in the highest energy level of the atom of an element.
What are valence electrons?
He first invented the Periodic Table.
Who is Mendeleev?
This is the number of electrons sodium has in its valence shell.
What is one electron?
This is the reason elements in a group have similar properties?
What are valence electrons?
These particles suggested that atoms may have a concentrated core. Explain how their behavior led Rutherford to conclude this.
What are alpha particles? Some particles traveled through the foil in a straight line, but many bounced off. This suggested that they were hitting a concentrated positive core.
What is the nucleus?
He theorized that atoms exist and developed four points describing how atoms behave.
Who is John Dalton?
This is how an electron can move to a higher energy level.
What is absorbing energy?