Atomic Structure and the Periodic Table

Atomic Structure and the Periodic Table Chapter 5 Chapter 5

The Structure of the Atom A. Three particles make up the structure of atoms: 1) protons …. positive charge (+) 2) neutrons … no charge (neutral) 3) electrons …negative charge (-)

B. These particles are located in one of two locations: 1) in the nucleus – protons and neutrons 2) around the nucleus - electrons

C. The mass of an atom is concentrated in the nucleus … Atomic mass = sum of protons + neutrons D. The Periodic Table indicates the number of protons in each element: Atomic number = number of protons * The atomic number identifies the element

E. Shorthand notation is used to indicate the element, atomic number and atomic mass: Carbon 6protons 6neutrons Sodium 11 proton 12 neutrons Hydrogen 1 proton 0 neutrons Hydrogen-1 Carbon-12 Sodium-23

Practice: Indicate the name, number of protons and number of neutrons

Isotopes A. “Atoms of the same element that have different atomic masses because they have different numbers of neutrons”

B. The atomic number identifies the element… C. The atomic mass = sum of protons + neutrons D. Only neutrons can change the atomic mass

Examples: Neon 10 proton 10 neutrons Neon 10 proton 12 neutrons Neon 10 proton 11 neutrons

90.48% 0.27% 9.25% What would be the atomic mass of neon? 20 x .9048 = 18.10 21 x 0.0027 = 0.06 22 x 0.0925 = 2.04 20.20

III. Electrons A. A NEUTRAL atom has the same number of electrons as protons B. ION – an atom that has a charge because it has lost or gained electrons

IV. The Periodic Table A. The periodic table is arranged in specific rows and columns according to their chemical behavior B. Specific regions have been named:

Representative Noble Gases Metals Period Group Non metals

Atomic Structure and the Periodic Table