Chemistry!

Atoms

100

What are the three subatomic particles of an atom?

Protons, neutrons, and electrons

200

What are three properties of electrons?

massless, negative charge, located in the electron cloud

300

If the atomic number is 6, how many electrons does this neutral element have?

6

400

If the atomic number is 4, and the atomic mass is 9, how many protons, neutrons, and electrons does this neutral atom have?

4 protons, 5 neutrons, 4 electrons

500

Atom A has 19 protons and 20 neutrons. Atom B has 20 protons and 20 neutrons. Atom C has 20 protons and 19 neutrons. Which of these two atoms represent the same element, and which element is it?

Atoms B and C; Calcium

Elements and the Periodic Table

100

Name 2 families of the periodic table.

Alkali metals Alkaline Earth Metals Halogens Noble Gases

200

Name one difference and one similarity between the alkali metals and the alkaline earth metals.

Difference: alkali metals have 1 bond to Hydrogen whereas alkaline earth metals have 2 bonds to Hydrogen. Alkali metals are more reactive than Alkaline Earth Metals. Similarity: both are metals, solids, and reactive

300

This element is reactive, a liquid at room temperature, is a nonmetal, and has one bond to Hydrogen. Which family does this element belong to?

Halogens

400

Explain why the periodic table is arranged in families with similar properties.

It helps us organize the elements and is an easy way for scientists to quickly recall characteristics of certain elements based on knowing where they are located in the periodic table.

500

Predict the properties (metal vs. nonmetal, reactivity, bonds to hydrogen, and phase state) of the element Argon.

nonmetal, not reactive, 0 bonds to hydrogen, gas

Chemical and Physical Properties

100

Define a chemical and physical change.

Chemical change= the substance undergoes a change in which a new substance is formed. Physical Change= the substance undergoes a change in which the sample retains its chemical identity.

200

Which one is NOT an example of a chemical change? A) frying an egg B) water boiling C) burning your test D) your bike rusting

B

300

Explain why phase changes (melting and boiling) are considered physical changes as opposed to chemical changes.

When a substance undergoes melting or boiling, the chemical identity does not change. For instance, when an ice cube melts, the molecules in solid H2O move further away from each other but we still have H2O molecules when we have liquid H2O.

400

Is flammability a chemical or physical property and why?

Flammability is a chemical property because it involves bond breaking/bond forming and the creation of a new substance with entirely different chemical properties. Also, burning something is an irreversible process.

500

Which families on the periodic table are most likely to undergo a chemical change? Explain your reasoning.

Alkali metals, Alkaline Earth metals, and Halogens. These three families are very reactive. All of them can form bonds to hydrogen.

Mixtures

100

What does it mean for something to dissolve? What are two pieces of evidence that you might observe if the solute dissolved in the solvent.

If something has dissolved in the liquid, that means it has pretty much disappeared into the solvent. You might see a change in color or you might just notice that there is less solute than earlier.

200

What is your evidence for a solute being partially soluble in a solvent? What is your evidence for a solvent being insoluble in a solvent?

Partially soluble means that not all of the solid has dissolved. You might see a color change in the liquid and a little less solute than there was before. If something is insoluble, the solute remains distinctly separate from the solvent.

300

Why is it that when I filter sugar water, my liquid is still sugar water, but when I filter sand and water, my liquid is primarily just water and the sand particles get caught in the filter?

Filter paper can only remove undissolved particles (ie. sand, malachite, etc.) but filter paper cannot remove dissolved particles, which is why the sugar, which dissolved in the liquid, seeps through the filter paper.

400

I mix 1 teaspoon of salt and 1 teaspoon of pepper into 1 cup of water. I then proceed to filter my mixture. If I were to collect the materials remaining in the filter, approximately how many teaspoons of solute would I find? Assume that we have not reached saturation.

I would find less than 1 teaspoon in the filter because some of the pepper and all of the salt would have dissolved in the water. Anything that has dissolved in the solvent will pass through the filter and we will not be able to collect it.

500

Define a homogeneous mixture and a heterogeneous mixture and provide examples of each.

A homogeneous mixture is any mixture that is uniform in composition throughout. Examples include tap water, air, perfume, vinegar, vegetable oil, etc. A heterogeneous mixture is any mixture that is NOT uniform in composition throughout. Examples include oil and water mixture, trail mix, etc.) Generally, you can fairly easily separate the components of a heterogeneous mixture.

Solubility

100

Define concentration.

Concentration is the measure of how much of a substance has been dissolved in a set amount of water.

200

Identify the solute and solvent in each solution. 1) hot chocolate 2) sweetened coffee 3) ocean 4) kool-aid drink

1) solute=hot chocolate powder; solvent=hot water 2) solute=sugar; solvent= coffee 3) solute=salt; solvent= water 4) solute=kool-aid; solvent= water

300

Which has a greater concentration? Cup A has 1 ml salt in 10 ml of water. Cup B has 10 ml salt in 100 ml of water. Explain your reasoning.

Concentration is the same because the ratio of salt to water is still the same. We just have a lot more salt water in Cup B.

400

Suppose I dissolved 2 ml of sugar in 5 ml of water in Cup A. I dissolved 2 ml of sugar in 10 ml of water in Cup B. Which has the higher concentration? Why?

Cup A because there is more ml of sugar per ml of water in Cup A. Since everything dissolved we can make this statement.

500

Suppose I added 5 scoops of salt into 10 drops of water into Container A, and 5 scoops of dominade into another 10 drops of water into Container B. It appears that 2.5 scoops of salt dissolved in 10 drops of water. The rest sits at the bottom. It appears that 4 scoops of dominade dissolved in the water. Does container A have higher, lower, or equal concentration as compared to container B. What is your reasoning?

Container A has a lower concentration than container B because less solute dissolved in the solvent