The atomic mass is the average mass of all the isotopes. The atomic number is the number of protons in the nucleus of an atom. In an uncharged atom the atomic number is also equal to the number of electrons.
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Answer:
In plants mitosis takes place throughout life in growing regions called the meristems. Replacements as cells wear out. The cells of the skin and bone marrow are sites of active mitosis replacing skin cells and red blood cells that only have a limited life. Repair.
Explanation:
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the answers are
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D. He could spray the fire extinguisher in the opposite direction of the space station
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<u>Answer:</u> The lewis dot structure is attached below.
<u>Explanation:</u>
A Lewis dot structure is defined as the representation of atoms having electrons around the atom where electrons are represented as dots.
A ketene is an organic compound having general formula R′R″C=C=O, where R and R' are two different/same monovalent chemical groups.
The given chemical compound having formula 
is represented as 
.
Total number of unshared electrons = 4 (left on oxygen atom only)
The lewis dot structure of is given in the image below.
1)
-Lithium: Lithium got 3 protons, so it atomic number is 3. It is located on the first column of the periodic table, and belonging to the alkali metal. So lithium is a metal. Lithium is highly reactive.
-Neon: It is located on the 18th column of the periodic table, and belong to the noble gases. So Neon is a nonmetal. Neon's reactivity is very low.
-Fluorine: Located on the 17th column of the periodic metal, fluorine is a nonmetal, and belong to the halogen family. Fluorine's reactivity is high.
2)
-Vertical columns of the periodic table are called columns. There is 18 column in the periodic table, and each one represent a chemical family.
-Horizontal rows of the periodic table care called periods. There is 7 periods in the periodic table.
-The number of protons in an atom is that element's atomic number. And since the atom is electrically neutral, the number of protons is equal to the number of electrons. So if you have the number of electrons, you can still find the atomic number.
-The total of protons and neutrons in an atom is that element's atomic mass. Based on the formula A = Z + N, where A represents the atomic mass, Z the atomic number (number of protons) and N the number of neutrons.
-The elements in group 1 are the most reactive metals. This group is called the Alkali metals. They only have 1 electron in their outer shell which makes them always ready to lose an electron in an ionic bonding.
-The elements in group 17 are the most reactive nonmetals. This group is called the Halogens, with 7 electrons in their outer shell which makes them always ready to win an electron in an ionic bonding.
-The elements in group 18 are the most unreactive elements. This group is called the Noble gases. Their outer shell is always full, so it can't do reactions.
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