The Structure of an Atom

1. The Structure of an Atom Section 4.2 Physical Science

2. Key Concepts What are the three subatomic particles? What properties can be used to compare protons, electrons, and neutrons? How are atoms of one element different from atoms of other elements? What is the difference between two isotopes of the same element?

5. Subatomic Particles Protons Neutrons Electrons Subatomic particles can be compared using their mass, charge, and location in the atom

6. Protons Positively charged Found in nucleus Number of protons in the nucleus determines atomic number of an element

7. Electrons Negatively charged Found outside nucleus Least massive particle (about 1/2000th the mass of a proton or neutron) A neutral atom will have the same number of electrons as it does protons

9. Neutrons Neutral (no charge) Found in nucleus Mass is similar to proton

11. Properties of Subatomic Particles

12. Classifying Atoms of Elements Atomic Number The atoms of any element always have the same number of protons Atomic number = number of protons in an atom of that element Atoms of different elements have different numbers of protons # p+ = #e- Mass Number Atoms of an element can have different numbers of neutrons than other atoms of the same element Mass number = number of protons + number of neutrons in the nucleus # neutrons = mass # - atomic #

14. Isotopes Every atom of a given element does not have the same # of neutrons. Isotopes of an element have the same atomic number (same # protons) but a different mass number than other isotopes of that element. This is b/c they have a different number of neutrons than other isotopes. Ex: carbon-12, carbon-13, carbon-14

16. Carbon Isotopes

17. REVIEWING CONCEPTS Name three subatomic particles. Proton, electron, and neutron. Name three properties you could use to distinguish a proton from an electron. Mass, charge, and location in an atom. Which characteristics of an atom always varies among atoms of different elements? Atoms of any element have a different number of protons than the atoms of all other elements. How are the isotopes of an element different fro one another? Isotopes of an element have the same atomic number but different mass numbers because they have different number of neutrons.