lab #4 periodic table – part 2

Lab #4Periodic Table – Part 2

Chemistry 108

Instructor:Robert Goldman

Periodic Trends – Electronegativity

Electronegativity is the attraction an atom has for its bonding valence electrons.

Electronegativity increases from left to right and from bottom to top of the periodic table.


The amount of energy required to remove a valence electron from an atom.

More electronegative atoms have higher ionization energies.

Periodic Trends – Ionization energy

Periodic Trends – Atomic size

Atomic size tends to increase LEFT to RIGHT across the periodic table and from TOP to BOTTOM down groups.

This is due to valence electrons occupying shells further from the nucleus.

Periodic Trends – Atomic size

Periodic Trends – Bonding Patterns

Elements usually form a certain number of bonds, depending on their location in the periodic table.

Group 14 elements (C, Si, Ge, Sn, Pb) tend for form 4 bonds.

For each group you move right, the normal number of bonds formed decrease by one.

Periodic Trends – Bonding Patterns

Therefore…– Group 14 elements tend to form 4 bonds.– Group 15 elements tend to form 3 bonds.– Group 16 elements tend to form 2 bonds.– Group 17 elements tend to form 1 bond.– Group 18 elements (noble gases) tend not to form

any bonds (stable). Hydrogen forms only one bond.

Chemical Nomenclature

You are expected to be able to provide appropriate names for simple binary and ternary compounds.

Binary = Two elements Ternary= Three elements

Naming Binary Compounds

Binary compounds begin with names based on the most metallic element present in the compound.

Ex. NaCl – sodium is more metallic than chlorine, so “sodium” is the first part of the name of this compound.


Next, the name of the less metallic element is added, with a suffix of –ide.

Ex. chlorine becomes chloride

Overall name of compound is sodium chloride.


How would you name the following?

– K2S

– MgO


Binary compounds can also form from two non-metals.

In this case, the name of the most metallic element (lowest in electronegativity) is used as the first part of the compound name.


When two non-metals combine, they can form several different compounds.

Unique names are assigned to distinguish these.

Remember these important prefixes!!!

1= mono 4= tetra

2= di 5= penta

3= tri 6= hexa


Example– Phosphorous and chlorine combine to form PCl3

and PCl5.

– In order to distinguish between the two: PCl3 is called phosphorous trichloride

PCl5 is called phosphorous pentachloride


How would you name the following?

– SiO2

– MgO4

IMPORTANT

DO NOT use these prefixes for compounds formed between a metal and a non-metal.

LiF is lithium floride NOT lithium monoflouride!


Compounds containing transition elements (center of the periodic table, no group #’s) are a bit different.

Most have a valence of two and form two bonds (+2 ion) by losing two electrons.

They may, however, form other ions by losing different numbers of electrons.


The charge of the transition element must always be shown in the name of the compound.

This is done by adding the charge in roman numerals in parenthesis after the ion.

Ex: Iron (II) oxide – Iron with TWO BONDS


So…– How many bonds does copper form in copper (II)

chloride? Cu forms one bond, Cl forms one bond-- CuCl

– What is the charge on titanium in titanium (IV) oxide?

Ti forms four bonds in this case, O (group VI) forms two bonds– TiO2

Naming Ternary Compounds

Ternary compounds contain three different elements.


Many of these are acids or salts of acids. Salt= compound formed from an acid + a base

– A salt is formed when the hydrogen from an acid is replaced by a metal.

Memorize the following acids:HClO3 =chloric acid HBrO3=bromic acid

HIO3=iodic acid H2CO3=carbonic acid

H2SO4=sulfuric acid H3PO4=phosphoric acid

HNO3=nitric acid (P. 94 in your textbook)


Chloric acid trends– HClO4 = perchloric acid (1 extra oxygen)

– HClO3 = chloric acid (base acid)

– HClO2 = chlorous acid (1 less oxygen)

– HClO = hypochlorous acid (2 less oxygens)

This is on P. 95 in your textbook.


Example:– HIO3 is iodic acid

– HIO2 becomes iodous acic

– Etc…


To name a salt of a ternary acid…– 1. Name the metal that replaced the hydrogen.– 2. Name the acid that the salt is derived from but

change the suffix to show the compound is no longer an acid (-ic becomes –ate,-ous becomes –ite).

Ex. LiNO3 has a base acid of HNO3 (nitric acid)– The salt will then be named lithium nitrate.


If an acid has two hydrogens, both are replaced to form a salt.

Group I metals replace one hydrogen each. Ex: Na2SO4 (derived from H2SO4)

– Name= sodium sulfate


Group II metals will replace two hydrogens each.

CaSO4 (derived from H2SO4)– Name=calcium sulfate

Today in lab…

We will be determining the percent water in a hydrated salt by weighing before and after dehydrating it.

Follow directions in lab manual. Be careful with hot crucibles! WEAR GOGGLES AT ALL TIMES! Let me know if you have questions.

lab #4 periodic table – part 2

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