Periodic Table and Chemical Families Science Learning Presentation 8 th Grade Success Oriented Lesson Plans
“Organizing” the elements ! We have seen the different elements have different characteristics. Is there any connection between the element’s place in the periodic table and its characteristic?
Dmitri Mendeleev 1834-1907 Mendeleev (a Russian chemist) organized in 1869 the elements in columns and rows. He integrated 63 elements recognized in his time. “Organizing” the elements !
Mendeleev’s Greatness It is amazing to see that the updated table of 2007, in which 115 element are written ( 23 of them are man made), is not so different from the one Dmitri Mendeleev invented in 1869. It is important to mention that the scientific world at Mendeleev’s period knew only 63 elements and scientists knew nothing about the atom’s structure. Only genius and daring caused this young scientists to create the connections.
His grate victory was by predicting elements that were not discovered yet! He left empty spaces with question marks for these elements, and added detailed characteristics he believed these elements will have.
1.According to an atomic number (the number of protons in the element’s atom). 2.According to the common characteristics of groups of elements. The elements were organized according to two criterions:
What is Mendeleev’s greatness? Question 1 A.He organized the elements in a table according to their atomic number B.He organized the elements in a table according to their characteristics C.He predicted and left room for elements yet to be discovered D.All of the above
Studying the periodic table shows that the elements are organized in columns and rows. Rows – The elements are organized according to an atomic number (rises from left to right). Columns – The elements are organized according to common characteristics.
Who was Marie Curie? Marie Curie was the first woman to win the Nobel price. In 1903 she won (along with her husband) the Nobel price for Physics and in 1911 she won the Nobel price for Chemistry. (Her daughter, Irène Curie, also won the Nobel price for Physics in 1935).
The connection between Marie Curie and the Periodic Table: Marie Curie discovered, along with her husband, the X-rays radiation. Think – Where will we be without this discovery! Her second scientific discovery was the discovery of the uranium and the radioactive radiation emitted by the uranium atoms.
Marie Curie died of cancer – a by product of long exposure to radioactive materials.
The elements in the periodic table are also organized in “big” groups: In addition to the columns and rows we can see that the elements are also organized in bigger chunks – the metals chunk and the nonmetals chunk. Nonmetals Metals
The nonmetals elements are located on the left side of the periodic table. Question 2 This sentence is: A.True B.False
Let’s learn about “Chemical Families”. “Chemical Family” A group of like characteristics located at the same column in the periodic table.
1.The Halogen family. 2.The Alkali metals family. 3.The Noble gasses family. To better understand the concept, we will focus on 3 chemical families: Let’s learn about “Chemical Families”.
What is a “Chemical Family”? Question 3 A.A group of elements with the same color. B.A group of elements located at the same row in the periodic table. C.A group of elements located at the same column in the periodic table. D.A group of elements with the same characteristics. E.Answers (C) and (D) are correct.
When looking for a replacement for a certain element, it is best to go to the column in which it is located in the periodic table.
The Alkali metals are located on the first column on the left (except hydrogen). The Alkali metals
Common characteristics: Solid in room temperature, electrical conductivity, soft, low-density, floats in water, react readily with halogens to form ionic salts, and with water to form strongly alkaline (basic) hydroxides. Examples: sodium, potassium, lithium. Uses: Mainly batteries. The Alkali metals
One of the Alkali metals characteristics is their readily reaction with water and nonmetals. Question 4 What is the recommended way to store Alkali metal? A.With oil B.With water C.With air D.With another metal
The Noble Gasses family The Nobel Gasses are located on the most right column (number 8 ).
The Noble Gasses family Common characteristics: These elements do no tend to create compounds, thus they exist in nature as elements. While in room temperature, they are in a state of gas. Examples: helium, neon, argon. Uses: lighting, welding, space technology.
Which gas is recommended for usage? Question 5 The hydrogen is a gas lighter than air and is a flammable material. In airships, the hydrogen was to be replaced with a gas lighter than air, does not readily ignite and does not react to other materials. A.Oxygen, which weigh as air B.Nitrogen, which does not react with other materials C.The noble gas helium, which meet all the requirements D.No gas can replace the hydrogen gas
A replacement can be found among the elements belonging to a chemical family called: Question 6 At a factory for manufacturing light bulbs, the argon gas which is used as an inert atmosphere for the inside of filament light bulb was exhausted. A.The halogen family B.The noble gasses family C.The alkali metals family D.There is no suitable chemical family
Why the elements in this “chemical family” are suitable to fill the light bulbs? Question 7 Electrical contact Insulation Cap (sleeve) Stem (glass mount) Glass bulb filament A.They do not conduct heat B.They are colorless C.They do not burn in oxygen D.They do not conduct electricity E.All of the above
The Halogen Family The Halogen family is located on the 7 th column from the right.
The Halogen Family Common characteristics: Highly reactive and can be harmful or lethal, create salt compounds with other metals, due to their chemical activity they do not appear as elements in nature, toxic. Examples: fluorine, chlorine, bromine, iodine. Uses: disinfection, utensils coating, cleaning and bleaching.
Let’s expound on the 4 halogens. Fluorine (F) – a poisonous, pale, yellowish brown gas. Used in toothpaste to prevent dental cavities. Bromine (Br) – a red volatile liquid at standard room temperature. Its vapors are corrosive and toxic. Used for manufacturing paint, photography materials, medications and fire-resistance cloths. Owing to their high reactivity, the halogens are found in nature only in compounds.
Additional Halogens: Chlorine (Cl) – it is a pale green gas and very poisonous. It has a disagreeable, suffocating odor. Was use as a weapon. Used in swimming pools to keep them clean and sanitary. Known as the cooking salt NaCl. Iodine (I) – a dark-purple/dark-brown solid. Turns into a violet-pink gas at standard temperatures. Used to disinfect wounds. It is also can be found in small quantities in the human body, and it is important for growth and development.
1.We use it for disinfection in everyday life. 2.It is used for filling light bulbs. 3.It is soft and react readily with water to form strongly alkaline (basic) hydroxides. Question 8 The following are 3 elements characteristics. Match the appropriate chemical family to the characteristic. A.(1) Alkali metals, (2) Noble gasses, (3) Halogens B.(1) Noble gasses, (2) Halogens, (3) Alkali metals C.(1) Halogens, (2) Noble gasses, (3) Alkali metals
Concepts Mapping Elements Nonmetals Halogens Fluorine Chlorine Nobel Gasses Helium Neon Metals Alkali Metals Potassium Sodium Other Metals Copper Iron
What characteristics we should look for when looking for an element to be used as a filament? Question 9 A.Electricity conductor and low melting temperature B.Not an electricity conductor and low melting temperature C.Electricity conductor and high melting temperature D.Electricity conductor and low melting temperature