2024 2nd semester 2/3

Any two atoms trying to form a chemical bond must be close to a balance position to form a bond. This diagram shows the two atoms too far apart, just right (balanced), and too close.

Using  the diagram below of two hydrogen atoms what is the most stable electron arrangement in terms of attractive and repulsive forces that make up the chemical bond ?

• When the electron cloud has very little attraction due to it's decreased density. This will allow for a bigger repulsive force between the positive nuclei than an attractive force between the electron cloud and the positive nuclei of the adjacent atom. This is a stable chemical bond.

• When the electron cloud has a strong attraction due to it's increased density. This will allow for a smaller repulsive force between the positive nuclei than an attractive force between the electron cloud and the positive nuclei of the adjacent atom. This is a stable chemical bond.

• When the electron cloud has a strong attraction due to it's increased density. This distance needs to be such that the repulsive force between the positive nuclei must equal attractive force between the electron cloud and the positive nuclei of the adjacent atom. This is a stable chemical bond.

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NGSS.HS-PS1-2

Any two atoms trying to form a chemical bond must be close to a balance position to form a bond. This diagram shows the two atoms too far apart, just right (balanced), and too close.

Using  the diagram below of two hydrogen atoms what is the most stable arrangement in terms of energy ?

• When the repulsive forces equal the attractive forces because this has a maximum potential energy for the bond.

• When the repulsive forces equal the attractive forces because this has a minimum potential energy compared to other arrangements .

• When the repulsive forces equal the attractive forces because this has no potential energy.

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NGSS.HS-PS1-4

Any two atoms trying to form a chemical bond must be close to a balance position to form a bond. This diagram shows the two atoms too far apart, just right (balanced), and too close.

Using  the diagram below of two hydrogen atoms what is the pattern of the attractive potential energy and attractive force that best describes the interactions. 

• Attractive potential energy is low the further away the two atoms are and then the closer they are the more attractive potential energy they have. Additionally, The attractive force is large the further away the the two atoms are and the force decreases the closer they are.  

• Attractive potential energy is high the further away the two atoms are and then the closer they are the less attractive potential energy they have. Additionally, The attractive force is small the further away the the two atoms are and the force increases the closer they are.  

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NGSS.HS-PS1-3

Compare H-H and He-He bonds below. Which is one has the greatest chance of forming a chemical bond and why ?

• He-He because the individual atoms potential energy is a lot greater than the molecules potential energy. By sharing electrons it becomes more stable do to the decrease in potential energy.

• He-He because there is not that much difference in the potential energy of the individual atoms and the molecule they would form. 

• H-H Because it has very little binding energy

• ​H-H because the individual atoms potential energy is a lot greater than the hydrogen H2molecule's potential energy. By sharing electrons it becomes more stable due to the decrease in potential energy.​

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NGSS.HS-PS1-4

NGSS.HS-PS1-2

​To get a hydrogen molecule H2 to break the bond that holds the two hydrogens together we need to do this ​

• ​The hydrogen molecule H2  bond can be broken by using a third atom with a lot of kinetic energy and force a collision or simply increase the temperature.​

• ​ Increase the kinetic energy of the hydrogen atoms to force the bond that makes the molecule H2​

• Increase the potential energy of the atoms that form the molecule

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NGSS.HS-PS1-5

In order to break the bond between atoms in a molecule, what needs to happen?

• A slow moving particle collides with the molecule and increases the potential and kinetic energy of the atoms.

• A fast moving particle collides with the molecule and increases the potential and kinetic energy of the atoms.

• A slow moving particle collides with the molecule and decreases the potential and kinetic energy of the atoms.

• A fast moving particle collides with the molecule and decreases the potential and kinetic energy of the atoms.

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NGSS.HS-PS1-5

How does the energy of the system change during an explosion?

• The kinetic energy of the system increases because the bonds between atoms are broken causing potential energy to increase.

• The kinetic energy of the system increases because the bonds between atoms are formed causing potential energy to decrease.

• The kinetic energy of the system decreases because the bonds between atoms are broken causing potential energy to increase.

• The kinetic energy of the system decreases because the bonds between atoms are formed causing potential energy to decrease.

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NGSS.HS-PS1-4

What effect does increasing the temperature of a substance have on the motion of its particles?

• An increased temperature means there is more energy in the substance and the particles will have an increased kinetic energy, so they move faster.

• An increased temperature means there is less energy in the substance and the particles will have a decreased kinetic energy, so they move slower.

• An increased temperature means there is less energy in the substance and the particles will have an increased kinetic energy, so they move faster.

• An increased temperature means there is more energy in the substance and the particles will have a decreased kinetic energy, so they move slower.

Tags

NGSS.MS-PS1-4

What happens to the atoms when a chemical reaction takes place?

• The number of atoms changes but the type of atoms are still the same. The atoms rearrange.

• The type of atoms changes but the number of atoms is still the same. The atoms rearrange.

• The number and type of atoms changes. The atoms rearrange.

• The number and type of atoms stays the same. The atoms just rearrange.

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NGSS.HS-PS1-7

Based on the energy diagram for this chemical reaction, how would you classify the overall energy change?

• Exothermic because the energy of the products is less than the energy of the reactants.

• Exothermic because the forming of bonds releases energy to the surroundings.

• Endothermic because the energy of the products is more than the energy of the reactants.

• Endothermic because the breaking of bonds requires energy to be absorbed from the surroundings.

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NGSS.HS-PS1-4