The Periodic Table October 17, 2013

In 1869 he published a table of the elements organized by increasing atomic mass by the way they reacted. Some problems: He left vacant spaces where unknown elements should fit.

Mendeleev’s Work

From his periodic table, Mendeleev was able to: 1.Correct atomic weights of already discovered elements (Be, In, U) 2.Predict elements that were not yet discovered (Sc, Ga, Ge, Ru) Sc=44 Ga=68Ge=72 Ru=100

After verification of the new atomic masses and the discovery of the unknown elements between 1874 and 1885, everyone generally accepted Mendeleev’s Periodic Table based on atomic masses!

-In 1913, through his work with X-rays, he determined the actual nuclear charge (atomic number) of the elements. - He rearranged the elements in order of increasing atomic number “There is in the atom a fundamental quantity which increases by regular steps as we pass from each element to the next. This quantity can only be the charge on the central positive nucleus.”

When elements are arranged in order of increasing atomic number, there is a periodic pattern in their physical and chemical properties.

The horizontal rows of the periodic table are called PERIODS.

The vertical columns of the periodic table are called GROUPS, or FAMILIES.

1.Elements in the same group have similar chemical and physical properties!! Why?? 2. They have the same number of valence electrons. V.E. = e- in outer shell. They lose and gain electrons at the same rate.

The Periodic Table: A More in depth Look

Periodic Table Broken into three sections: Metals Non-metals Metalloids Where is the break line?

Take out your yellow periodic table Lets label the metalloids: Put a star next to the metalloids on your table: –Boron (B) (group 13) –Silicon (Si), Germanium (Ge) (group 14) –Arsenic (As), Antimony (Sb) – Group 15 –Tellurium (Te), Polonium (Po) – Group 16 –Astatine (At) – Group 17 - Put a key at the top of your table to indicate the metalloids.

A. Properties of All Metals Found to the left and underneath of the stair step line. 1. Malleable – Can be hammered or rolled into shape (Al foil, thin sheets) 2. Ductile – Can be drawn into wires (Cu wires for your all electrical goods) 3. Good conductors of heat and electricity. 4. Luster – Ability to reflect light (makes them shiny) 5. Combine with non-metals by losing electrons. 6. All metals (except 1) are solid at room temperature. Thoughts????

B. The Non-Metals Located to the right of the stair step line 1. Brittle – The ones solid at room temperature break easily. 2. Low Boiling Point- Most are gases at room Temperature. 3. Poor conductors of heat and electricity.

C. The Metalloids 1. Located along the stair-step line on the PT. 2. Ability to conduct heat and electricity varies. 3. Good insulators at low temps and good conductors at high temps.

Families on the Periodic Table 1. Groups are also grouped into families. 2. Families = 1 column or many columns. (1 group or more)

Hydrogen 1. Hydrogen belongs to a family of its own. 2. Hydrogen is a diatomic (two atoms) reactive gas. 3. Label Hydrogen on your blank periodic table.

Just an FYI….. There are 7 diatomic elements on the periodic table, meaning they always are found with two atoms linked together. Aside from Hydrogen, they form a “7” on the periodic table. Starting with N, O, F, Cl, Br, I The Magnificent Seven!!!!! (You will need to remember these later, when we write chemical equations.

Alkali Metals 1. 1 st column on the periodic table (Group 1) not including hydrogen Valence electron 3. Very reactive metals, always combined with something else in nature (like in salt). 4. Soft enough to cut with a butter knife

Alkali Metals Common elements are Sodium (Na), Potassium (K) and Lithium (Li). Lithium is used to make batteries. Label the Alkali Metals on you Blank Table.

Alkali Metals

Alkaline Earth Metals 1.Second column on the periodic table. (Group 2) 2.2 valence electrons 3. Reactive metals that are always combined with nonmetals in nature. 4. Mg and Ca are common alkaline earth metals. 5. They are important minerals to sustain life. 6. Label the Alkaline Earth Metals on you Blank Table.

Transition Metals 1.Elements in groups Valence electrons are random 3. Less reactive metals than group 1 and Gold, Silver, Iron, Copper 5. Metals used “as metal.”

Boron Family 1.Elements in group valence electrons 3. Aluminum metal is found in the group. Al is the most abundant metal in the earth’s crust.

Carbon Family 1.Elements in group valence electrons 3. Contains elements important to life and computers. 4. Carbon is the basis for an entire branch of chemist ry. 5. Silicon and Germanium are used for computer chips

Nitrogen Family 1.Elements in group valence electrons 3. Nitrogen makes up over ¾ of the atmosphere. 4. Nitrogen and phosphorus are both important in living things.. 5. N and P are used in making fertilizers.

Oxygen Family 1.Elements in group valence electrons 3. Oxygen is necessary for respiration, breathing. O is the most abundant element in the earth’s crust.

Halogens 1.Elements in group valence electrons 3. Very reactive, volatile, diatomic, nonmetals 4. Always found combined with other elements in nature. 5. Chlorine, Fluorine, Iodine 6. Used as disinfectants (kill life) 7. Halo – means salt formers

The Noble Gases 1. Elements in group Full valence shell 3. Do not react with anything in nature. 4. Neon, Argon, Helium 5. Neon lights – when excited with electricity, these gases will produce color.