Periodic Table song (3 mins)
Elements Compounds and Mixtures- History of Elements and Chemical Symbols
Download this file: Yr 8 Elements and Symbols
Part (A) – Elements and the Chemical Symbols (Reading)
WHAT IS AN ELEMENT?
A substance that cannot be broken down into simpler substances by chemical reactions. Atoms of the elements are identical. All atoms of the same element have the same physical properties (size of the atom) and the same chemical properties. Scientists arranged all the elements they knew or they discovered in a periodic table.
SYMBOLS of ELEMENTS:
A chemical symbol (or a chemical formula) is a shorthand method of representing an element. Instead of writing out the name of an element, we represent an element name with one or two letters. The periodic table is a chemist’s easy reference guide.
The symbols used by earlier scientists (Dalton and other scientists in 1808 – 1815) are quite different from symbol that appeared in the periodic table published by Mendeleev 1861, scientists used to obtained the modern periodic table.
Part B: WHAT YOU ALREADY KNOW about the SYMBOLS of elements in a periodic table.
PART C: INVESTIGATIONS: – Answer all the questions below:
|Number||Name of element||Chemical Symbol||Solids, liquids or gases at room temperature||Metals, non-metals or metalloids.|
Part E Research. (Group work) and presentation.
Choose an element in the table above (one element per student in the group) and answer the questions below. Prepare a minute presentation per student in the group.
Name of element: _____________________ researched by _____________ (student name.
RUBBING YOUR SHOES ON CARPET CAN “ZAP” YOU. WHY?
The ancient Greeks discovered that rubbing amber with fur or other objects, it could pick up things like feathers! They may have discovered electricity. Electricity comes from the Greek word elector, which means ‘beaming sun’. This name came about because amber had a rich yellow glow in the sunlight.
Have you had any of these experiences?
Static electricity is made when materials rub together. The more they rub together, the more electricity is made. This means bigger sparks. When you rub or brush a rod with a cloth, you rub off electrons. Having too many electrons makes a negative charge, and having too few electrons makes a positive charge. A spark is formed when electrons jump from where there are too many electrons to where there are too few.
The study of static electricity forces is called electrostatics. An uncharged plastic rod has an equal number of positive and negative charges. The negative charges are called electrons. Because they are at the edge of the atoms, electrons are easy to rub off. When you rub or brush a rod with a cloth, you rub off electrons. Sometimes the electrons are rubbed off the rod onto the cloth. And sometimes the electrons are rubbed off the cloth onto the rod.
Static electricity occurs with many non-metal materials. There is an electric field around objects which have an electric charge.
Elements Compounds and Mixtures- 1.What are the early ideas of atom?
Download the word document: Survey and History of Atoms: Yr 8 Element C M_Survey and history of atoms
WHAT YOU ALREADY KNOW – Survey
Part (A) What you already know- Survey and Discussion.
Answer the questions below:
PART (B) HISTORY of ATOMS – What were the early ideas? Who
HISTORY OF ATOMS – What were the early ideas of atoms?
Democritus (460-370 B.C.) Ancient Greece
His ideas of atoms:
Main idea: Democritus introduce the idea that matter is made up of atoms. All atoms of same matter are identical. Atoms of different matter are different.
Dalton, England: (1803) Ideas of atom:
Atoms of same elements have the all same mass, atoms can be rearrangeed in a chemical reaction to form compounds.
JJ Thomson: (1897)
|1.What are the early ideas of atom (particle theory/kinetic theory of particles)?|
|2. What is the smallest unit of an element?|
|3. What is an element?
How scientists derived symbols for the elements for the first twenty on the periodic table.
What are the symbols of other transition metals – Zinc , Iron , Silver, Gold, Mercury?
|4. How elements are classified as metals, non-metals and metalloids on a periodic table?
Do elements in the same group have the same properties?
|5. Where are groups 1 and 2 and group 3 and 4 located on the periodic table?
Are groups 1 and 2 metals? Are groups 7 and 8 non-metals?
Which of the elements are gases and solids at room temperature?
|6. Where are the subatomic particles –protons, neutrons and electrons (these are smaller than atom) located in an atom? Who discovered these subatomic particles and what technological devices assisted in their discoveries?|
|7. How the subatomic particles (protons, neutrons and electrons) arranged within the atom e.g Helium atom?|
|8. How can scientist tell the difference between elements, compounds and mixtures?|
|9. How models can be used to show the difference between molecules e.g. monoatomic (Helium), diatomic H2, metallic, chains (C3H8). How models can be used to compare structure and diamond?|
|10. Are these everyday substances such as water, sugar, tea, air, blood and bread classify as elements, compounds or mixtures? What are the composition of each of these substances?|
|11. Can Hoffmann voltameter show that water is a compound and that it can be decomposed to form oxygen and hydrogen?
Can a new compound be made by heating magnesium in a flame?
|12. What are uses and special properties of the ten substances that changed the world? Research the five compounds that changed the world? In which cultures are these materials used?|
|13. What are the useful properties of silica that allows it to be used in optical fibres? How the optical fibres are used in endoscope and optical fibre communications?|
|14, What are the reasons for using polymer money in Australia?|
|15. Is there a need to continually develop new pharmaceuticals? Why should scientists be encouraged to do research into these products?|
Static Electricity – Summary
Basic rules: Like charges repel. AND Opposite charges attract_.
An atom is made up of two parts – a positively charged nucleus surrounded by negatively charged electrons. In an uncharged (neutral) atom, there is the same number of positive and negative charges.
The charge can build up in a big way, causing voltages as high as 50,000 Volts. A shock_ from this doesn’t kill you, as the actual amount of charged particles stored on the dome is so small.
1. Two types of charges: positive and negative.
|Attractive force exists||Repulsive force exists|
|A positively charged object and a negatively charged object.||A positively charged object with another positively charged object.|
|A neutral object and a positively charged object.||A negatively charged object with another negatively charged object.|
|A neutral object and a positively charged object.|
3. Objects with no charge do not attract each other. A comb that is not charged will not pick up pieces of paper. Objects which are charged can pick up pieces of paper.