Bohr model of a helium atom Atomic Structure Bohr model of a helium atom -An atom consists of a nucleus made of protons and neutrons that is orbited by electrons

Atomic Structure -The number of protons, not electrons or neutrons, determines the unique properties of an element -The number of protons is called the element’s atomic number -Most of the time, the number of protons will be the same as the number of electrons

Atomic Structure -The size of a nucleus is very small (10,000 to 100,000 times smaller than the atom), but the nucleus contains almost all the mass (protons + neutrons). -The electrons occupy a large area around the tiny nucleus, and this is what determines the size of an atom. If the nucleus (1 proton) of a hydrogen atom were as large as the width of a human thumb, the electron would be on the average about a little more than half a mile away with only empty space in between

Atomic Structure

Atomic Structure Subatomic Particles p+ e- n0 proton electron neutron Symbol p+ e- n0 Charge +1 -1 Mass 1 1/1837

Elements on the Periodic Table atomic number element symbol element name atomic weight Label the four parts of this element.