ATOMS AND THE PERIODIC TABLEchapter three

ATOMIC THEORY - history3.1 Atomic Structure

ATOMIC THEORY - STRUCTURE MODEL OF THE ATOMELECTRON -ENERGY LEVELS3.1 Atomic Structure

ATOMIC STRUCTURE ELECTRON LOCATIONElectrons are found in energy levels of an atom. Electrons occupy the lowest energy level available.3.1 Atomic Structure

Energy Levels are like ladder rungsGAINING ENERGY3.1 Atomic Structure

Energy Levels3.1 Atomic Structure

ORBITALS where the electrons are located within an energy level.S orbital(Like a sphere)may contain up to 2 electronsfirst energy level is an s orbital3.1 Atomic Structure

P orbital

(Like a dumbbell)may contain up to 2 electronssecond energy level may contain an s orbital and up to 3 p orbitals3.1 Atomic Structure

Orbitals3.1 Atomic Structure

Valence electrons are located in the outermost energy level of an atom.They determine the chemical properties of an element.3.1 Atomic Structure

3.2 A TOUR OF THE PERIODIC TABLEProperties of elements change in a regular pattern that the table helps to describe.

Periods Horizontal Rows

Groups(families) Vertical Columns

Traditional Periodic TableLos Alamos National Laboratory's Chemistry Division Presents a

Periodic Table of the Elements

3.2 Guided Tour of Periodic Table

The number of protons in an atom determines an elements location on the table.

3.2 Guided Tour of Periodic Table

Elements On the Periodic Table6CCarbon12.001ATOMIC NUMBERSYMBOLNAMEMASSPROTONS(and ELECTRONS too) PROTONS+ NEUTRONS MASS #3.2 Guided Tour of Periodic Table

1118001PROTONS AND NEUTRONS HAVE EQUAL MASS. ELECTRONS ARE TINY 1800 EQUAL ONE PROTON.3.2 Guided Tour of Periodic Table

MASS 35ATOMIC NUMBER 17

Clprotons _?_electrons _?_ neutrons _?_3.2 Guided Tour of Periodic Table

MASS 35ATOMIC NUMBER 17

Clprotons 17electrons 17 neutrons 35-17 = 183.2 Guided Tour of Periodic Table

IONS are atoms that have lost or gained an electron.ELECTRON GAINED =NEGATIVE CHARGE(-)

ELECTRON LOST =POSITIVE CHARGE(+)3.2 Guided Tour of Periodic Table

Na+ClElectrontransfer3.2 Guided Tour of Periodic Table

TWO KINDS OF IONS:A (+) CHARGED ION IS A Cation.

A (-) CHARGED ION IS AN Anion.EXAMPLES:LITHIUMFLUORIDE3.2 Guided Tour of Periodic Table

The atoms of an element always have the same number of protons.BUT..The atoms of an element may have different numbers of neutrons.This is an ISOTOPE!Two carbon ISOTOPES:CARBON 12 = 6 protons and 6 neutronsCARBON 14 = 6 protons and 8 neutrons3.2 Guided Tour of Periodic Table

The AVERAGE MASS of an ATOMWhy is the mass number not an even number?Atoms of the same element exist with different numbers of neutrons.This makes the mass of different atoms of the same element different.The average mass is a weighted number so that more common isotopes have a greater affect on the average than rare isotopes.What is an amu?It is an atomic mass unit.An amu is equivalent to the mass of 1/12 of a carbon-12 atom.3.2 Guided Tour of Periodic Table

3.3 FAMILIES OF ELEMENTS:HAVE THE SAME VALENCE NUMBER.HAVE SIMILAR CHEMICAL AND PHYSICAL PROPERTIES.A COLUMN OF ELEMENTS IS A FAMILY.

TWO MAJOR DIVISIONSMETALSNONMETALS3.3 Families of Elements

GROUP ONE:ALKALI METALSVERY REACTIVEONE VALENCE ELECTRON3.3 Families of Elements

GROUP TWO:ALKALINE EARTH METALSTWO VALENCE ELECTRONS3.3 Families of Elements

GROUP 3-12:TRANSITION METALSMANY COMMON METALSNOT AS REACTIVE AS OTHER METALS3.3 Families of Elements

GROUP 17:HALOGENSVERY REACTIVEFORM SALTS WITH ALKALI METALS7 VALANCE ELECTRONS3.3 Families of Elements

GROUP 18:NOBLE GASESINERT / UNREACTIVEEIGHT VALENCE ELECTRONS3.3 Families of Elements

SYNTHETIC ELEMENTSThey are man-made and radioactive.They include all elements above #92, plus #43 and #61.3.3 Families of Elements

SEMICONDUCTORS (METALOIDS)The elements that are between the metals and nonmetals are known as:SEMICONDUCTORS (METALOIDS)They may exhibit metallic and nonmetallic properties.3.3 Families of Elements

3.4 USING MOLES TO COUNT ATOMSSome counting units: Reams of paperDozens of eggsAtomic mass units of protons and neutronsMoles of atomsA mole is the SI unit that describes the amount of a substance.Avogadros constant is the number of particles in one mole which = 6.022 x1023 molar mass is the mass in grams of one mol of a substanceit is equal to the average atomic number of an atom.

Chapter 3Studying for the TestVocabularyParts of an atomHistoryElement familiesUsing the periodic tableMetal vs. nonmetal