Ch. 7.1 - Part 1 -

The ElementsCHM Hon.

First, things to Remember…

• What is IONIZATION ENERGY? What is the general trend?

• What is ELECTRONEGATIVITY? What is the general trend?

• What are the REPRESENTATIVE ELEMENTS and why are they called “representative”?

Properties of s-block elements

• There are 92 naturally occurring elements in the Universe

Properties of s-block elements

• Representative elements– Group 1A – 7A– Valence electrons: # and location determine

the chemical properties• Metals: tend to lose electrons• Nonmetals: tend to gain electrons

Properties of s-block elements

• Diagonal relationships– The close relationship between elements in

neighboring groups

Properties of s-block elements

• Diagonal relationships– Some period 2 elements do not behave as

predicted by their location on the p.t.– Period 2 elements have more in common with

period 3 elements in the next group

Properties of s-block elements

• HYDROGEN– Group 1A– 1 Valence electron– Not part of any specific group

• Has properties of a metal and a nonmetal

Properties of s-block elements

• HYDROGEN– Discovered by Henry

Cavendish 1776• Flammable air

Properties of s-block elements

– HYDROGEN• Named Hydrogen by Lavoisier 1783

– “to form water” hydro + genes

Properties of s-block elements

• HYDROGEN– Universe is more than 90 % H by mass– 3 isotopes

• Protium (99.9%) H-1• Deuterium H-2

– Used in nuclear reactors - “heavy water”

• Tritium H-3

Properties of s-block elements

• HYDROGEN– Acts like both a metal and nonmetal– Nonmetal

• Gains an electron• Acquires the stable electron configuration of He

– Metal• Acts like a metal when reacting with a nonmetal • Loses its single electron becomes a H+ ion