AboutRalph Salier-Hellendag Expertise Science Fair Judge for many years and experience with robotics, biology, chemistry, industrial processes, metalurgy and metal forming.
Experience Science Fair Judge for many years and have helped several students get to state level competition. Most recently 2 of my students received state level awards and one went on to the nationals in Washington DC.
Education/Credentials BA Archaeology - Anthropology
MA Business Anthropology
Question QUESTION: for a school project we have to choose an element from the periodic table. we are asked to draw an atom of this element. I've tried researching but nothing looks right,
please give me a detailed diagram of an atom
ANSWER: Hi Sam,
You have selected wisely. This is a simple atom.
Calcium: Ca
Atomic Number: 20
Atomic weight: 40.08
Electron Shells: 4 ( 2 in the first - K) (8 in the second - L) (8 in the third - M) and (2 in the fourth - N)
In the neucleous you will find 20 positrons and either 19, 20 or 21 neutrons.
So, when drawing this atom, in the center draw 40 circles the size of a dime or small coin, color 20 of them blue and put a "+" sign in side of them. The neutrons, leave white.
Then around the outside draw 6 big circles. These represent the shells. On the one closest to the neucleaus, put two small circles. These will represent the electrons. They should be on opposite sides of the circle. Color these red and place a "-" inside. On the next circle put two more small circles and color these red with a "-" inside. On the third circle place 6 of these but spaced equally around the circle. On the 4th circle place 2 of them again opposite from each other, on the 5th circle place 6 equally spaced around the circle like #3 and on the last circle 2 opposite from each other.
You can have these circles on different "planes" or at different angles so that it looks like the atom is surrounded by electrons.
I wish I could draw it for you but this site does not allow this.
Good Luck.
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QUESTION: Is there a web site someone could please give me that as a picture of a calcium atom
It looks sort of like the image at this web site but this is a very simplistic view. It also only show 4 of the 6 shells.
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QUESTION: I got asked this question in my science project: why did the number 2 appear in front of the compound and why did we not use brackets around the compound and place a number 2 at the end?
eg. 2H2O instead of (H20)2
please help me i can't find the answer anywhere
Answer Hi Sam,
When doing a chemical formula or when trying to determine the out come of a chemical reaction, the proper way to indicate the number of Molecules of a substance resulting or to be included in the reaction is as you have noted, in the front of the molecule. Thus 2 H2O indicates 2 molecules of water.
To place the 2 at the end may be confused with H2O2 which is also a type of reactive molecule.
