Organization of Matter

S1-2-03 Define element and identify symbols of some common elements. S1-2-06 Investigate the development of the periodic table as a method of organizing elements. S1-2-08 Relate the reactivity and stability of different families of elements to their atomic structure. Vocabulary & People Period Non-metals Group Family Alkali metals Earth metals Chalcogens Halogens Noble gases Mendeleev

Elemental symbols originated from a Greek or Latin root word Modern Symbols Alchemist Symbols Dalton Symbols Antimony Sb   Arsenic As Bismuth Bi Carbon C Copper Cu Gold Au Iron Fe Lead Pb Mercury Hg Silver Ag Sulpher S Tin Sn Zinc Zn

Russian scientist and professor Mendeleev (1870) Russian scientist and professor Arranged the 63 elements by atomic mass Noticed a repetition of properties (periodicity) Called the pattern of properties “Periodic Law” Mendeleev (correctly) predicted the mass of elements yet to be discovered and left spaces open for them

Repetition of properties (periodicity) became more clear Moseley (1913) Experiments showed proton number was a better method to organize the elements. Repetition of properties (periodicity) became more clear Modern Periodic Law: “The properties of elements are a periodic function of increasing atomic number” We know now that most element properties are due to the number of valence electrons – luckily electron and proton numbers are equal

M e t a l s The Periodic Table contains metals and non-metals. A staircase separates metals from non-metals. Non- metals M e t a l s

Element with properties opposite to those of metals (brittle, dull…) Rows of the periodic table are called periods. Elements in periods do not have similar properties Left to right Elements change from metals to non-metals Non-metal Element with properties opposite to those of metals (brittle, dull…) periods

Family names and locations need to be memorized Columns of the periodic table are called groups. Elements in groups have similar properties A family is a group with a specific name: Family names and locations need to be memorized GROUP Alkali metals Alkaline Earth metals Chalogens Halogens Inert (noble) gases

Older tables have an old label system for columns with Roman numerals – new tables just number them 1 through 18

Simplest atomic structure - only 1 e- and 1 p+ Hydrogen* Group 1 Non-metal gas 1 valence electron Simplest atomic structure - only 1 e- and 1 p+ Highly chemically reactive The placement of hydrogen is only because of its structure - 1 proton… Sometimes a table will have it raised above the Alkali Metals to avoid confusion

What trends (“periodicity”) have you found?

The Octet Rule of Chemical Reactions Atoms with a FULL outer orbit are very stable Chemical reactions happen when atoms work together to try to get a full valence orbit Atoms will acquire a full outer shell in 3 ways: Give away an e- to another atom Take an e- from another atom Share an e- with another atom We’ll skip this one until next year

+ Sodium atom: Sodium ion: 11 p+ 11 p+ 11 e- 10 e- Na Na + Once a neutral atom gains or loses e- to be more stable it is called an ion

- Chlorine atom: Chlorine ion: 17 p+ 17 p+ 17 e- 18 e- Cl Cl - Notice the ion has a charge associated with it based on the number of e- lost or gained

2+ Calcium atom: 20 p+ 20 e- Ca Calcium ion: 20 p+ 18 e- Ca 2+

3- Nitrogen atom: 7 p+ 7 e- N Nitrogen ion: 7 p+ 10 e- N 3-

Increasing Reactivity The LESS electrons needed, the GREATER the chemical reactivity of the element Increasing Reactivity A Chemical Reaction Movement of electrons between combining atoms that results in the formation of a NEW substance.

A new substance is formed Working together to become more stable is what binds atoms (now called ions) together to make compounds. A new substance is formed - + explosive metal toxic gas Salt!

CAN YOU ANSWER THESE QUESTIONS? S1-2-06 How is the Periodic Table organized for the elements and what trends exist? S1-2-03 What are the symbols of the first 20 elements and other common ones? S1-2-08 Why do families react differently during chemical reactions? Vocabulary & People Non-metals Period Group Family Alkali metals Earth metals Chalcogens Halogens Noble gases Mendeleev