DO NOW

1) How many neutrons does Oxygen – 18 have?

2) Draw and complete the chart shown below.

Isotope !

Oxygen Carbon Helium Gold Silicon

Chemical Symbol

Protons

Electrons

88

O C66

He22

Au

7979

Si1414

n = mass # - atomic # n = 18 - 8n = 10

L.O.SWBAT explain how the periodic table is organized.

Title: Atoms and the Periodic Table

Electrons in the atomspectrum: 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 atomsEach individual color in a spectrum is

called a spectral line because each color appears as a line in a spectroscope.

Bohr model of the atomDanish 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 theoryQuantum 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 theoryGerman 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 levelselectron cloud The energy levels occur because

electrons in the cloud are at different average distances from the nucleus.

Models of energy levelsBohr’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.

matter vs anti-matter

Elements andthe Periodic Table

Everything is awesome!

Elements andthe Periodic Table

Physical PropertiesSee, Hear, Smell

Chemical PropertiesChange into a new substance

color 2 H + O = H2O

texture Rusting (iron + oxygen)

density Burning

state (solid, liquid, gas)

Chemical Reaction

melting point Oxidation

boiling point

specific heat

The Periodic Table

Remember -

The periodic table is organized by increasing atomic number.

Atomic Numberatomic 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

Incre

asin

g A

tom

ic 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

period

Groups of the periodic tableGroup 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 Gasesor 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