CHEMISTRY MIDDLE SCHOOL

HELP WILL MARK BRAINLISTWhich of the diagrams is the correct model for the element beryllium?

#12
rachel2005smith avatar

Answers

Answer 1
Answer:

Answer:

B is the correct model of beryllium.

Explanation:

An atom consist of electron, protons and neutrons. Protons and neutrons are present with in nucleus while the electrons are present out side the nucleus.

All these three subatomic particles construct an atom. A neutral atom have equal number of proton and electron. In other words we can say that negative and positive charges are equal in magnitude and cancel the each other. For example if neutral atom has 6 protons than it must have 6 electrons. The sum of neutrons and protons is the mass number of an atom while the number of protons are number of electrons is the atomic number of an atom.

For example  in case of beryllium:

The atomic number of beryllium is 4.

The atomic mass is 9 amu.

Number protons = 4

Number of electrons = 4

Number of neutrons = 9-4 = 5

So b is correct answer because 5 neutrons and 4 protons are present with in nucleus while 4 electrons are present out side.
Answer 2
Answer:

I believe your answer is B.

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Answers

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Answers

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Cu + AgNO3 = Cu(NO3)2 +Ag

Answers

The problem is that you have to balance Cu + AgNO3 = Cu(NO3)2 + Ag

The first step is to identify all the elements and how many atoms of that element there are on either side of the equals sign.
When you do this you will get,
 
1 Cu 1
 1 Ag 1
 1 N 2
 3 O 6

Next step is to make sure that all the elements are the same on both sides. This is mostly trial and error until you balance both sides. 

The solution to the equation would be:

Cu + 2AgNO3 = Cu(NO3)2 + 2Ag

So now if you check your elements, you will get the following:

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As you can see all the elements are equal on both sides, so the equation is balanced.

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Answers

We can observe physical properties of elements and compounds without changing the substance.

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Answers

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Express 975,000 in scientific notation

Answers

9.75 x 10^5

A number in scientific notation has the form a x 10^b where

• a is the coefficient

• b is the exponent

Here are the steps to convert a number greater than 1 to scientific notation.

a) Find the coefficient

Put the decimal point after the first digit and drop the trailing zeroes

9.75 000

The coefficient is 9.75.


b) Find the exponent

Count the number of digits after the first digit.

In 975 000 there are five digits after the 9. Therefore, the exponent is 5.

c) Write the number

We write 975 000 as 9.75 x 10^5.
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