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rosijanka [135]
3 years ago
5

2. Perform this operation and report the answer to the correct number of significant figures: What is the mass of a cube of alum

inum that is 4.0 cm on each edge? The density of aluminum is 2.7 g/cm3. Show all calculations leading to an answer.
3. Explain why a model of the atom is crucial to understanding chemistry and in explaining the behavior of matter. Use 3 - 4 sentences in your explanation.

4. What parts of Dalton’s atomic theory no longer agree with the current picture of the current picture of the atom? Provide an answer using at least 3 to 4 complete content related sentences in your own words.

5. If an element has 12 protons and 17 neutrons, how many electrons must it have?
Chemistry
1 answer:
lyudmila [28]3 years ago
7 0

2) D = m/V. Knowns: V = (4 x 4 x 4) = (64) D = 2.7

2.7 = m/(64)

172.8 = m or with significant figures, 170

3) Knowing the model of the atom is crucial becuase without understanding what everything is made up of, then there is no way of telling how it is going to react with outside things. Knowing the model of the atom can better help us visualize what it looks like and it can also tell us how it is going to react baced on its propertys and what it is made of.

4) Dalton's theory tells us that 1, all matter is made of atoms, which are indivisible and indestructiable. This does not agree with todays findings because we know that atoms can be broken up into sub atomic particals, and even those sub atomic particals can be broken down even further to sub-sub-atomic particals such as quarks and borons. 2, We also know about Isotopes. Isotopes are the same atom but with different atomic weights becaus of the amount of nutrons in the nuclei.

5) If an element has 12 protons and 17 neutron, in order to be stable and found in nature, the atom must have 12 protons because protons are positive and neutrons have a charge of 0 so in order to balence the atom out, the electrons, with a negitive charge, must be the same number as the protons.

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1. How many ATOMS of boron are present in 2.20 moles of boron trifluoride ? atoms of boron.
maks197457 [2]

Answer:

1. How many ATOMS of boron are present in 2.20 moles of boron trifluoride? atoms of boron.

2. How many MOLES of fluorine are present in  of boron trifluoride? moles of fluorine.​

Explanation:

The molecular formula of boron trifluoride is BF_3.

So, one mole of boron trifluoride has one mole of boron atoms.

1. The number of boron atoms in 2.20 moles of boron trifluoride is 2.20 moles.

The number of atoms in 2.20 moles of boron is:

One mole of boron has ---- 6.023x10^2^3 atoms.

Then, 2.20 moles of boron has

-=2.20 mol. x 6.023 x 10^2^3 atoms /1 mol\\=13.25x10^2^3 atoms

2. Calculate the number of moles of BF3 in 5.35*1022 molecules.

(5.35x10^2^2 molecules/6.023x10^2^3)x 1mol\\=0.0888mol

One mole of boron trifluoride has three moles of fluorine atoms.

Hence, 0.0888moles of BF3 has 3x0.0888mol of fluorine atoms.

=0.266mol of fluorine atoms.

5 0
2 years ago
What greek letter are used in the precise definition of a limit?
Ivan
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The diagram shows a simple lipid.
kifflom [539]
This is not a phospholipid as it does not contain a phosphate group at the end of the chain, and is not a triglyceride as there is no glyceryl moiety. Each carbon bonded to hydrogens makes the maximum number of C-H bonds possible, therefore there are no multiple bonds between carbons and the lipid is saturated. Therefore the answer is A.
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7 0
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The nuclei of atoms also contain neutrons, which help hold the nucleus together. ... The total weight of an atom is called the atomic weight. It is approximately equal to the number of protons and neutrons, with a little extra added by the electrons.


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