How many atoms of calcium are there?

How many bonds will Oxygen form?

How many bonds will Nitrogen form?

How many bonds will Carbon form?

How many bonds will Hydrogen form?

Ethanol is a substance that can be used as fuel. Its molecular structure is shown to the right.

Scientists want to label the fuel with the formula. Which of the following is the formula for ethanol?

Scientists are using ammonia in a new cleaning product. They know that the formula for ammonia is NH₃. Which model represents ammonia?

Joel is a clothes designer. He decides to look into polyester, which is a synthetic material, as a possible material to use in a new line of kids’ clothing. He wants to use a material that would be a good choice for children and has as little negative effect on the environment as possible. He reads the following information on polyester. Joel decides to not use polyester for his new clothing line. Which reason might he provide to support his choice?

Kenya’s doctor diagnoses her with a Vitamin E deficiency and writes a prescription for synthetic Vitamin E tablets. One tablet provides Kenya 100% of her recommended daily intake of Vitamin E.

Kenya also looks into where she might be able to find Vitamin E naturally, as she knows it is found in some types of nuts and seeds. She finds some information on foods that contain Vitamin E. The chemical formulas for natural and synthetic Vitamin E are shown in the table. Which is true about the synthetic version of Vitamin E? Select one answer.

Diamonds and graphite are two substances made from the same type of atom. Even though they are made from the same type of atom, these substances have very different properties.

The models in Figure 1 show extended structures for diamonds and graphite.

Which of the extended structures in Figure 2 is built from the same atom as diamond and graphite? 

Atoms and molecules are the basic building blocks of matter.
Determine if the model in the top row of the table represents an atom or a molecule. 

Atoms and molecules are the basic building blocks of matter.
Determine if the model in the middle row of the table represents an atom or a molecule. 

Atoms and molecules are the basic building blocks of matter.
Determine if the model in the bottom row of the table represents an atom or a molecule. 

two or more atoms joined together—atoms can be either the same element or different elements

any substance made by humans by mixing or reacting natural materials together

the smallest unit of a chemical element—everything that exists is made up of these

a substance that has a constant proportion and arrangement