DO NOW 1)How many neutrons does Oxygen – 18 have? 2) Draw and complete the chart shown below. Isotope ! OxygenCarbonHeliumGoldSilicon Chemical Symbol Protons Electrons 8 8 OC 6 6 He 2 2 Au Si n = mass # - atomic # n = n = 10

L.O. SWBAT explain how the periodic table is organized. Title: Atoms and the Periodic Table

Electrons in the atom  spectrum: Each element has its own characteristic pattern of colors  The colors of clothes, paint, and everything else around you come from this property of elements to emit or absorb light of only certain colors.

Electrons in atoms  Each individual color in a spectrum is called a spectral line because each color appears as a line in a spectroscope.

Bohr model of the atom  Danish physicist Neils Bohr proposed the concept of energy levels to explain the spectrum of hydrogen.  When an electron moves from a higher energy level to a lower one, the atom gives up the energy as different colors of light.

The quantum theory  Quantum theory says that when things get very small, like the size of an atom, matter and energy do not obey laws of classical physics.

The quantum theory  German physicist Werner Heisenberg (1901– 1976)  The uncertainty principle explains why a particle ’ s position, momentum or energy can never be precisely determined.  The uncertainty principle exists because measuring any variable disturbs the others in an unpredictable way.

The uncertainty principle

Electrons and energy levels  electron cloud  The energy levels occur because electrons in the cloud are at different average distances from the nucleus.

Models of energy levels  Bohr ’ s model of electron energy levels is incomplete.  Energy levels are predicted by quantum mechanics, the branch of physics that deals with the microscopic world of atoms. quantum mechanics  matter vs anti-matter matter vs anti-matter

Elements and the Periodic Table  Everything is awesome! Everything is awesome!

Elements and the Periodic Table Physical Properties See, Hear, Smell Chemical Properties Change into a new substance color2 H + O = H 2 O textureRusting (iron + oxygen) densityBurning state (solid, liquid, gas)Chemical Reaction melting pointOxidation boiling point specific heat

The Periodic Table  Remember -  The periodic table is organized by increasing atomic number.

Atomic Number  atomic number = number of protons  If the atom is neutral, it will have the same number of electrons as protons.

Atomic Mass  The mass of individual atoms is so small that the numbers are difficult to work with.  To make calculations easier, scientists use the atomic mass unit (amu). 32 amu

Elements are organized into rows called periods. There are 7 periods. Metals are on the left of the table, with the most reactive metals on the far left. Decreasing reactivity of metals Increasing Atomic Mass

Elements are organized into columns called groups. There are 18 groups. Groups consist of elements with similar characteristics. –Example, Group 1 elements react violently with water, Group 2 react slowly with water or not at all.

The Periodic Table  Big Idea: Elements in the same group form similar compounds and have similar properties.  Group 1- 2 atoms of the metal to 1 atom of oxygen.

Inert gases group period

Groups of the periodic table  Group 1 = alkali metals.  The alkali metals are soft and silvery in their pure form and are highly reactive.  This group includes the elements lithium (Li), sodium (Na), and potassium (K).

15.1 Halogens  Group 17 - halogens tend to be toxic gases or liquids in their pure form.  Fluorine (F), chlorine (Cl), and bromine (Br) - when they bond with alkali (group 1) metals they form salts.

Noble Gases  or Inert gases  Group 18 - do not naturally form chemical bonds with other atoms and are almost always found in their pure state.

Summary  Write a paragraph (at least 4 sentences)  What is the Big idea from today’s lesson?  Use your notes to support your big idea statement.

COSMOS  Packet Q & A