All categories

3 years ago

PLEASE ANSWER Which is/are true?

Chemistry

1 answer:

Alona [7]3 years ago

3 0

You have to check each statement, so this is equivalent to 5 different questions.

Answers:

The true statements are:

b. Si has valence electrons in the n = 3 energy level.

d. Xe has valence electrons in the n = 5 energy level.

Explanations:

a. Li has valence electrons in the n = 1 energy level.

Answer: False.

Valence electrons are the electrons in the outermost main energy level (shell of electrons).

To determine where the valence electrons are, you build the electron configuration, using Aufbau rules to predict the orbital filling: in increasing order of energy.

The atomic number of lithium (Li) is 3. Hence, you have to distribute 3 electrons, and so its electron confiuration is:

1s² 2s¹

The only valence electron is in the 2s orbital, i.e. in the n = 2 energy level.

b. Si has valence electrons in the n = 3 energy level.

Answer: True

Silicon (Si) has atomic number 14, so you have to distribute 14 electrons in increasing order of energy:

1s² 2s² 2p⁶ 3s² 3p²

Thus, Si has five valence electrons, and they are in the n = 3 energy level.

c. Ga has valence electrons in the n = 3 energy level.

Answer: False

Gallium has atomic number 31, so you have to distribute 31 electrons, filling the orbitals in increasing order of enery.

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p¹

The highest energy level is 4. This is where the valence electrons are. So, Ga has the valence electrons in the n = 4 level (not n = 3 as the statement describes).

d. Xe has valence electrons in the n = 5 energy level.

Answer: True

The atomic number of Xe is 54.

Using the short notation (noble gas notation), and filling the orbitals in increasing order of energy, you get the configuration:

[Kr] 5s² 4d¹⁰ 5p⁶.

Hence, the valence electrons are in the n ) 5 level, such as the statement describes.

e. P has valence electrons in the n = 2 energy level.

Answer: False

Phosphorus (P) has atomic number 15, hence there are 15 electrons.

The electron configuration following the increasing order of energy, which you can remember using Aufbau rules, is:

1s² 2s² 3s² 3p³

Then, the valence electrons are in the n = 3 energy level; not in the n = 2 energy level.

You might be interested in

What important discovery did Ernest Rutherford make?

EleoNora [17]

Answer:

D if im pretty sure

Explanation:

In 1909 he began experiments that were to change the face of physics. He discovered the atomic nucleus and developed a model of the atom that was similar to the solar system.

7 0

3 years ago

Read 2 more answers

Which of the following instruments is used to measure air pressure?

timama [110]

Barometer, it is used to measure air pressure

5 0

3 years ago

A chemistry student must separate should barium sulfate from the aqueous solution. Equipment and glassware normally found in the

Elan Coil [88]

If there's just some barium put in an aqueous solution, then it should be something like this.
It's a mixture of a solution and an insoluble solid, so the easiest way to go is through filtration. (Also, I'm assuming the barium is cut into very small chips.)

In a line, simply filter the solution using a folded filter paper in a funnel, collect the residue in a beaker or flask, rinse it with distilled water and let it dry. (Or simply filtering it could be enough, depending on how far your teacher wants you to go.)

Stuff needed:
>filter paper (for separating the solid from the solution)
>funnel (to hold the filter paper)
>beaker or flask (to hold the filtrate)
>distilled water (to rinse the solid)
>spatula (to scoop up the solid)

Procedure:
>Fold filter paper and line the funnel with it. Place the funnel in the flask or beaker.
>Pour solution in. Then add water (I think using tap water might be fine in this case, but you can use distilled water if you'd like) to wash out the container with the solution of any solid you may have not gotten in the first try. Alternatively, you could use a spatula to spoon it onto the filter paper.
>Once everything has been filtered, pour some distilled water on the residue on the filter paper to wash away the solution.
>Take out the filter paper, open it up and let it dry.

This can be used in real life in many occasions. For example, when you make tea, you need to filter the leaves out. Or when you cook the pasta, you put it in a sieve to separate the pasta from the water. Or when you fish using fishing nets, you "filter" the fish from the water.

6 0

3 years ago

PLEASE HELP ASAP FOR 25 POINTS!! :D

kondaur [170]

the x y axis is tipped so the earth is flat

3 0

3 years ago

A type of plate boundary that is transform faults (easily seen where they cut at right angles to the mid-ocean ridges) A.) conve

34kurt

The answer is Option C (Divergent Plate Boundary)

Mapping efforts have shown that mid-ocean ridges are discontinuous structures that cut at right angles to its length at various transform faults. They typically demarcate the boundary between two tectonic plates, and are therefore called divergent plate boundaries.

8 0

3 years ago