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3 years ago

Which statement is true about electrons that are in an atom's highest energy levels?

Chemistry

1 answer:

Stella [2.4K]3 years ago

5 0

Answer:

The valence shell has higher energy than other occupied shells

Explanation:

According to Bohr's model of the atom, he suggested that the extranuclear part consists of electrons in specific spherical orbits around the nucleus.

His model suggests that the electron can move round the nucleus in certain permissible orbits or energy levels. The ground state is the lowest energy state available to the electron. The excited state is any level higher than the ground state.

The valence electrons are in the outermost shell of an atom. These electrons are of the highest energy levels in the atom

THANKS

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What does a base release when it is placed in water?

Alexxx [7]

Answer:

D - Hydroxide Ion (OH-)

Explanation:

A base provides either hydroxide ions (OH–) or other negatively charged ions that combine with hydrogen ions, reducing their concentration in the solution and thereby raising the pH. In cases where the base releases hydroxide ions, these ions bind to free hydrogen ions, generating new water molecules.

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3 years ago

1. The horizontal columns on the periodic table are called

Anna11 [10]

Answer:

Periods

Explanation:

The vertical columns on the periodic table are called groups or families because of their similar chemical behavior. All the members of a family of elements have the same number of valence electrons and similar chemical properties. The horizontal rows on the periodic table are called periods.

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4 years ago

Read 2 more answers

Which type of cell is larger

Karo-lina-s [1.5K]

Answer: eukaryotic cell

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3 years ago

You are given stocks of 4 M NaCl, 40% Glucose, and 1M Tris-HCl (pH 8.5). You need to make 400 ml of a buffer containing 0.5 M Na

OLga [1]

Answer:

50mL of 4M NaCl, 80mL of 40% glucose, 20mL of 1M Tris-HCl (pH 8.5) and 250mL of water.

Explanation:

To make 400mL containing 0.5M NaCl you need to add:

4M / 0.5M = 8 (dilution 1/8). 400mL / 8 = 50 mL of 4M NaCl.

Glucose 8% you need to add:

40% / 8% = 5 (dilution 1/5). 400mL / 5 = 80 mL of 40% glucose 

Buffer 50mM you need to add:

1000mM / 50mM = 20 (dilution 1/20). 400mL / 20 = 20mL of 1M Tris-HCl (pH 8.5)

The resting volume: 400mL - 50mL of 4M NaCl - 80mL of 40% glucose - 20mL of 1M Tris-HCl (pH 8.5) = 250 mL must be completed with water.

Thus, to make the solution you need: 50mL of 4M NaCl, 80mL of 40% glucose, 20mL of 1M Tris-HCl (pH 8.5) and 250mL of water.

I hope it helps!

8 0

3 years ago

How many grams of C5H12 must be burned to heat 1.39 kg of water from 21.2 °C to 97.0 °C? Assume that all the heat released durin

faust18 [17]

Answer:

m = 8.9856 g

Explanation:

In order to do this, we need to write the expressions that are to be used. First, to calculate heat:

Q = m*C*ΔT (1)

Where C would be heat capacity of the substance.

The heat can also be relationed with the moles and enthalpy of a compound using the following expression:

Q = n*ΔH (2)

Finally for the mass of any compound, we use the following expression:

m = n*MM (3)

So, in order to calculate the grams of pentane (C5H12), we need to calculate the moles of the compound, and to do that, we need the heat exerted.

So, as we are using water, let's calculate the heat that is been exerted with the water. The C of the water is 4.186 J/g °C so:

Q = (1.39 * 1000) * 4.186 * (21.2 - 97)

Q = -441,045.33 J

This is the heat neccesary to burn pentane and heat water. Now, with this value, let's calculate the moles used of pentane with expression (2). The ΔH of the pentane is -3,535 045.kJ/mol or -3.535x10⁶ J/mol. Solving for n we have:

n = -441,045.3 / -3.535x10⁶

n = 0.1248 moles

Finally, we can calculate the grams needed with expression (3). The molar mass of pentane is 72 g/mol

m = 0.1248 * 72

m = 8.9856 g

This is the mass needed to heat 1.39 kg of water

6 0

4 years ago