Mateo observes a white crystal that is cube-shaped under a microscope.Slightly white, almost clear cubes on a black background.Based on this observation, Mateo thinks the crystal could be sodium chloride (table salt). Because the crystal has an extended structure, he knows that sodium chloride is not a molecule. Mateo uses gray and black spheres, representing the atoms in sodium chloride (NaCl), to make a model of the crystal's most likely structure, as shown.A set of interconnecting cubes. The cubes share sides and corners. At each corner is a small black ball or a large gray ball. The colors alternate between the corners.Select all of the reasons why the model accurately represents sodium chloride.(2 points)ResponsesMateo used gray to represent the sodium atoms and black to represent the oxygen atoms.Mateo used gray to represent the sodium atoms and black to represent the oxygen atoms.Sodium chloride is composed of four kinds of atoms.Sodium chloride is composed of four kinds of atoms.Mateo's model shows a repeating pattern of sodium and chlorine atoms.Mateo's model shows a repeating pattern of sodium and chlorine atoms.The model can be extended to show larger amounts of sodium chloride.The model can be extended to show larger amounts of sodium chloride.Skip to navigation

Answer 1

The two valid reasons why Mateo's model accurately represents sodium chloride are:

1. Mateo's model shows a repeating pattern of sodium and chlorine atoms.

   • This accurately reflects the arrangement of ions in sodium chloride, which forms a cubic lattice structure where sodium (Na⁺) and chloride (Cl⁻) ions alternate.

2. The model can be extended to show larger amounts of sodium chloride.

   • Sodium chloride's structure is a crystalline lattice, meaning that it can be repeated indefinitely, which is characteristic of ionic compounds.

The other statements regarding the colors representing different atoms are inaccurate in the context of sodium chloride (NaCl), as NaCl consists of sodium and chlorine, not sodium and oxygen, and does not consist of four kinds of atoms.

Answer 2

Choose all descriptions that are true for chemical changes.(2 points)ResponsesCutting down a tree is an example of a chemical change.Cutting down a tree is an example of a chemical change.The chemical and physical properties change during a chemical reaction.The chemical and physical properties change during a chemical reaction.The identity of the substance stays the same.The identity of the substance stays the same.There are the same number of atoms before and after the change.

Answer 3

The true descriptions for chemical changes are:

1. The chemical and physical properties change during a chemical reaction.

   • This is true because a chemical change results in the formation of new substances with different properties.

2. There are the same number of atoms before and after the change.

   • This statement is true according to the law of conservation of mass, which states that atoms are neither created nor destroyed in a chemical reaction.

The other statements are false:

• Cutting down a tree is an example of a chemical change. (This is actually a physical change; it changes the location of the tree, but not its chemical composition.)

• The identity of the substance stays the same. (This is false; a chemical change results in the formation of new substances, which means the identity of the original substance changes.)

Answer 4

Which of the following is NOT true about synthetic materials?(1 point)ResponsesSynthetic materials are made by humans.Synthetic materials are made by humans.Synthetic materials can have positive and negative impacts on society.Synthetic materials can have positive and negative impacts on society.Natural resources are made from synthetic materials.Natural resources are made from synthetic materials.Synthetic materials are made from natural materials.

Answer 5

The statement that is NOT true about synthetic materials is:

Natural resources are made from synthetic materials.

This statement is incorrect because natural resources come from nature and are used to create synthetic materials, not the other way around. Synthetic materials are human-made and can be derived from natural resources.

Answer 6

Which item is made of synthetic materials?(1 point)Responsesaluminum foilaluminum foilplastic forkplastic forkwooden deskwooden deskcotton shirt

Answer 7

The item made of synthetic materials is:

Plastic fork.

Plastic is a synthetic material, created through chemical processes, whereas aluminum foil, wooden desk, and cotton shirt are made from natural materials.