Presentation on theme: "THE STRUCTURE OF ATOMS Pg. 43. Daily science- pg. 40 Who discovered the neutron? Electron? Nucleus? What did Democritus theorize? Name two differences."— Presentation transcript:
Daily science- pg. 40 Who discovered the neutron? Electron? Nucleus? What did Democritus theorize? Name two differences between the old atomic theory and the new atomic theory?
What makes up an atom? Atoms are made of subatomic particles. The three subatomic particles are the proton, electron, and neutron.
Structure of an atom The nucleus is located at the center of the atom. It contains positively charged particles, called protons, and neutral particles, called neutrons. Most of the mass is located here.
Structure of an atom Electrons, or negatively charged particles, exist outside of the nucleus in the electron cloud.
Subatomic Particles chart ParticleChargeMassLocation Proton+ 11.67 x 10 27 In the nucleus Neutron 01.67 x 10 27 In the nucleus Electron9.11 X 10 31 Outside the nucleus
Atomic Number The periodic table can be used to find the number of protons, electrons, and neutrons. The atomic number of an element (labeled Z) tells you how many protons there are. On the periodic table, the elements are listed as neutral elements so the number of electrons=the number of protons.
Mass Number The mass number (labeled A) is the number of neutrons + protons. It is located under the element symbol. You can find the number of neutron by subtracting the Atomic number (Z) from the Mass number (A) A-Z = # of neutrons
Writing Atomic mass and number There is a way to represent atomic mass and number Steps: 1-start with the element symbol 2- place the mass number on the top left side of the symbol 3-place the atomic number on the bottom left side of the symbol
Isotopes An isotope is an element that has the same number of protons but a different number of neutrons. Ex. Carbon has 2 common isotopes: Carbon-12 Carbon-14 The numbers represent the mass number
Determining the number of neutons Ex. Carbon 12 and Carbon 14