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

Element 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    

Elemental symbols originated from a Greek or Latin root word

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

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

Moseley (1913)Experiments showed proton number was a better method to organize the elements.

• Repetition of properties (periodicity) became more clear

The Periodic Table contains metals and non-metals.

A staircase separates metals from non-metals.

M e t a l sNon- metals

Rows of the periodic table are called periods. • Elements in periods do not have similar properties

Left to rightElements change from metals to non-metals

per

iod

s

Non-metalElement with

properties opposite to those of metals

(brittle, dull…)

Columns of the periodic table are called groups. • Elements in groups have similar properties

A family is a group with a specific name:

• Alkali metals• Alkaline Earth metals• Chalogens• Halogens• Inert (noble) gases

GROUP

Family names and locations need to be memorized

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

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 atomWe’ll skip this one until next year

Sodium atom:11 p+

11 e-

Na

Sodium ion:11 p+

10 e-

Na +

+

Once a neutral atom gains or loses e- to be more stable it is called an ion

Chlorine atom:17 p+

17 e-

Cl

Chlorine ion:17 p+

18 e-

Cl -

-

Notice the ion has a charge associated with it based on the number of e- lost or gained

Calcium atom:20 p+

20 e-

Ca

Calcium ion:20 p+

18 e-

Ca 2+

2+

Nitrogen atom:7 p+

7 e-

N

Nitrogen ion:7 p+

10 e-

N 3-

3-

The LESS electrons needed, the GREATER the chemical reactivity of the element

A Chemical Reaction Movement of electrons between combining

atoms that results in the formation of a NEW substance.

Incr

easi

ng R

eacti

vity

Working together to become more stable is what binds atoms (now called ions) together to make compounds.

+ -

explosive metal toxic gas

A new substance is formed

Salt!

CAN YOU ANSWER THESE QUESTIONS?

S1-2-06How is the Periodic Table organized for the elements and what trends exist?

S1-2-03What are the symbols of the first 20 elements and other common ones?

S1-2-08Why do families react differently during chemical reactions?

Vocabulary & People

Non-metals Period Group

Family Alkali metals Earth metals

Chalcogens Halogens Noble gases

Mendeleev