1. Discussion Substances Melting Point °C Boiling Point °C Astanine 302
337
Sulfur
112
444
Cesium 28
678
Bromine -7 58
Mercury
-38
356
Chlorine
-100
-34
Discussion
Which of the above elements are gases at 350°C?
Which of the above elements will undergo a phase change when the temperature increases from -50°C to 100°C?
Which of the above elements have the greatest boiling point?
Which of the above elements have the lowest boiling point?
Which of the above elements are liquids at 0°C?

2. Elements and The Periodic Table

3. Elements & Compounds Elements: simplest form of matter
Building blocks of all matter
All represented on the periodic table with an element symbol.
1 Letter – Capital
2 Letters – 1st Capital, 2nd Lowercased
Compounds: combination of two or more atoms combined with new properties/characteristics than the individual elements did alone
Sugar: Carbon (black solid) + Water (colorless liquid)
Water: Oxygen (colorless, non-flammable gas) + Hydrogen (colorless, flammable gas)
Compounds are in definite proportions and written in chemical formulas. Most chemical formulas contain subscripts to represent the proportions to each element in the compound.

4. History of the Periodic Table
Dmitri Mendeleev, Russian chemist, hoped to organize the elements according to their properties.
Placed each element on a card, with atomic mass, and physical and chemical properties.
Then arranged them according to properties and trends or patterns.
Noticed that they were arranged in order of increasing atomic mass, similarities in their chemical properties appeared at regular intervals as well. Thus the name periodic, repeating pattern.
His for table was produced in You can notice a few of the elements seem “out of place” from where they currently are placed.
He also left a couple empty spaces in his periodic table. He predicted the existence and properties of three elements. Today these elements are: scandium, gallium, germanium.

6. History of the Periodic Table
In 1911, English scientist – Moseley, worked with Rutherford (gold foil experiment man) examined the spectra of 38 different metals.
Discovered that the elements fit better into the periodic table if they were arranged by the number of protons in the nucleus.
Thus atomic number, not atomic mass.
Moseley’s discovery was consistent with Mendeleev’s ordering of the periodic table by properties rather than strictly by atomic mass.
Mendeleev’s principle of chemical periodicity is correctly stated in what is known as the periodic law – the physical and chemical properties of the elements are periodic functions of their atomic number.

7. Current Periodic Table
The periodic table is an organized way of looking at the elements.
The elements are arranged according to similarities in properties
Many scientists have worked on refining the periodic table. It started with Mendeleev who organized the elements by the atomic mass doing up and down to Moseley who organized the elements going horizontally by atomic number (#of protons)
There are a few different key points in the periodic table:
Groups/Families – vertical columns in which the elements have similar physical and chemical properties
1A-8A are the representative elements in the main group elements. They represent all states of matter: s, l, g
1B-8B are the transition elements. As you move from left to right across the middle of the table the elements transition from metals to nonmetals.
Inner Transition Metals – two rows on the bottom – rare earth metals and those not found in nature
Periods – horizontal rows
Number of elements per period: 2, 8, 8, 18, 18, 32

9. Metals, Nonmetals, Metalloids
80% of all known elements are metals
Characteristics are based on their functional properties as well as their appearances
Physical: shiny, malleable, ductile, tensile strength, solid (not Hg), conductivity
Nonmetals
20% of known elements are nonmetals
Found on the right side of the periodic table
Physical: hard, brittle, gases (not Br, I, S, P, C, Se), poor conductor
Metalloids
Border both sides of the “stairs”
Have some metal and nonmetal properties
7 Solids: B, Si, As, Te, At, Ge, Sb
Used in computers, digital watches, TVs, radios