1. Homework:Review NotesChapter 4 Packet

2. Chapter 4 Section 1 Introduction to Atoms

3. The Modern Atomic Model • In 1932, scientist James Chadwick discovered another particle in the nucleus of the atom • Neutron • Hard to detect due to no electric charge • Nearly the same mass as a proton

4. The Modern Atomic Model

5. Particle Charges • Protons are positively charged (p+) • Electrons are negatively charged (e-) • Neutrons have no charge (n)

6. Particle Charges

7. Comparing Particle Mass • Although electrons may balance protons charge-for-charge, they cannot compare when it comes to mass. • Approximately 2000 electrons equal 1 proton • A proton and a neutron are about the same mass • Protons and neutrons make up nearly all the mass of an atom.

8. Comparing Particle Mass

9. Atomic Number • Every atom of a given element has the same amount of protons • All forms of oxygen have the same number of protons (8) • All forms of carbon have the same number of protons (6) • The number of protons in a nucleus of an atom is the atomic number.

10. Atomic Number

11. Isotopes and Mass Number • Atoms of the same element that have a different number of neutrons are called isotopes. • An isotope is identified by its mass number, which is the sum of the protons and neutrons in the nucleus of the atom.

12. Isotopes Assignment • You’re task is to diagram the three different carbon isotopes (pg. 130) • You will need to explain: • Why each carbon atom is considered an isotope? • How many protons and neutrons help compose each carbon isotope? • Which isotope of carbon has the largest mass number?