WoC Ch 3.8 Intro to the Periodic Table

Objective: Learn about various features of the periodic table

Objective: Learn some of the properties of metals, non-metals, and metalloids

Periodic Table

6C

12.001

Elements are listed

• A chart that shows all of the known elements and gives a lot of information about each

Atomic number

Chemical symbol

Mass Number

• On the periodic table in order of increasing atomic number

More arrangement…

1869 Russian scientist

Arranged by families

Chlorine and Fluorine behave similarly, as do potassium and sodium

What are the atomic numbers of Cl, F, K, and Na

• Elements are also arranged in specific horizontal rows and vertical columns

• Dmitri Mendeleev-Father of the Periodic Table

• Mendeleev arranged the P.T. this way because of similarities in the chemical properties of various “families” of elements

• The periodic table refers to the fact that as we increase the numbers, every so often an element occurs with properties similar to those of a lower number element

• ____,____,____,____

Vertical columns are called

Groups are often referred to by

See Discovery School Circle Periodic Table

Many groups have special names

Group 1Group 2

Group 7 (17)Group 8 (18)

Large collection spanning many vertical columns

• Families and/or Groups

• The number over the column

• For simplicity we delete all of the “A”s

Alkali Metals

Alkaline Earth Metals

Halogens

Noble gases

Transition metals

Relatively small number of elements in the upper right hand corner of the

periodic table

Many non-metals areOne is liquid

Several non-metals are

Elements that lie close to the stair-step line

• Non-Metals– Lack characteristics of

metals– Have more variation in

their properties

GaseousBromine (Br)Solids

Metalloids or Semi-metalsShow a mixture of

metallic and non-metallic properties

Most elements are metals

• Physical properties– Efficient conduction of

heat and electricity– Malleable– Ductile– A lustrous (shiny)

appearance– Most metals are solid

at room temperature

Knowledge of the Periodic Table…

Is extremely useful in the study of chemistry!

1. Describe most of the elements on the periodic table.

2. List one element that is liquid at room temperature.

3. What information is usually found in each individual square of the periodic table?

WoC Chapter 3.9 Natural States of the Elements

Objective 1: Learn the natures of the common elements

Define Compound

Noble Metals(Relatively unreactive)

Group 8

Air sample yields

Diatomic molecules

Atoms from different elements are chemically bonded

Gold, Silver, Platinum

Noble Gases: He, Ne, Kr, Xe, Rn

Pure element, existing as single atom: Argon

Diatomic molecules: N2 & O2

Molecules made of 2 atoms

7 Diatomic Molecules to know

Most elements in Group 7 and Group 8

2 are liquids in elemental form

Non-metallic structures are more varied

Ex:

H,N,O,F,Cl,Br,I are all diatomic molecules

Are gases at room temperature (25°C)

Hg (Mercury) andBr (Bromine)

Allotropes-elements whose atoms make different forms

Carbon:Diamond, graphite, buckminster

fullerene

WoC Chapter 3.10Ions

• Objective 1: Describe the formation of ions form their parent atoms and learn to name them.

• Objective 2: Predict which ion a given element forms by using the periodic table.

Q: If an atom has a certain number of

protons in the nucleus and an equal number of electrons in its

valence shell, what can be said about the overall charge

of the atom?

A: The fact that the number of protons and electrons is equal results in an exact balance of positive and negative charges. Thus, an atom is neutral. It has zero net charge!!

IonTake a neutral atom

Add an electronRemove an electron

Ex: Sodium atom Z=11

One electron is lost

11+ + 10- = 1+

CationAnion

CationsMg Mg2+ + 2e-

Al Al3+ + 3e-

• A charged entity

negative ion forms

positive ion forms

11 protons

11 electrons11+

10-

Na Na+ + e-

Positive ion

Negative ion

Magnesium forms a 2+ cation

Aluminum forms a 3+ cation

Cations are named

Sodium NaMagnesium Mg

AnionAnions

Chlorine Cl + e-

Fluorine F + e-

Bromine Br + e-

Iodine I + e-

• Using the name of the parent atom

• Na+ Sodium ion• Mg2+ Magnesium

• Negatively charged ion• Gain electrons

• Cl-

• F-

• Br-

• I-

Anions are named

Chlorine becomes

Some atoms gain 2 electrons

ex: Oxygen O + 2e-

Sulfur S + 2e-

Ions are always formed

• By taking the root name of the atom and changing the ending to –ide

• Chloride

• O2- oxide ion• S2- sulfide ion

• By removing electrons from an atom or adding electrons to an atom

IONS ARE NEVER FORMED BY

Isolated atoms do not form ions on their own

When metals and nonmetals react

Metals and nonmetals tend to form

compounds that

• CHANGING THE # OF PROTONS!!!

• Most ions are formed when metallic elements combine with nonmetallic elements

• Metal atoms tend to lose one or more electrons, which are in turn gained by atoms of the nonmetal

• Contain metal cations and nonmetal anions

WoC Chapter 3.11Compounds That Contain Ions

• Objective 1: To describe how ions combine to form neutral compounds

Chemists have reason to believe that many chemical compounds

contain ionsConsider common table

salt (NaCl)

As a solidWhen meltedPure water

but when salt is dissolved in water

• 800°C to melt• 1500 °C to boil• Will not conduct electricity• Is a very good conductor• Will not conduct electricity

• The solution readily conducts electricity

These properties are best explained by picturing NaCl as containing Na+ ions and Cl- ions

Sodium chloride breaking apart (ionizing) in solution

Electric current can travel along a metal

wire because

The moving electronsIn ionic substances

Thus, substances that contain ions can

conduct an

Electrons are free to move through the wire

Carry the current

the ions carry the current

Electric current only if the ions can move.

Electron movement in wire and ionic substances

The body uses ions in the Sodium/Potassium Pump in Cell

membranes

In solid NaCl, ions are tightly held and cannot

move. However,

As a result, an electric current can travel

through

The same reasoning applies to NaCl dissolved

in water

• When solid is melted and becomes liquid, the structure is disrupted and the ions can move

• The melted salt!

• When the solids dissolve, the ions are dispersed in the water and can move!

We recognize substances that contain

ions

Many substances contain ions

These substances are called …

A chemical compound must have

• By their characteristic properties.

1. Very high melting point

2. Conduct electricity when melted or dissolved in water

Whenever a compound forms between a metal and a nonmetal, it can be expected to contain ions.

IONIC COMPOUNDS

A net charge of zero!

If a compound contains ions 1. There must be both

positive (cations) ions and negative (anions) ions.

2. The number of cations and anions must be such that the net charge is zero

Na+ + Cl- NaCl

Na+ + Cl- NaCl

Mg2+ + O2- MgO

More Ionic Bonding

Remember this Periodic Table trend?

When bonding…

1. You must have ions: anions and cations2. When they combine, the resulting

compound will have no net charge3. This means that the number of atoms of

each element must be accounted for so that the number of anions and cations in the compound is the same

4. You notate the number of atoms needed by using subscripts. Ex: Na2O, MgCl2