Chemistry Matters Trivia Quiz

Answer: It occupies space.

This is the definition of matter. Having mass means it can be weighed - the earth's gravity can exert a force on it. Occupying space means that it has some physical size, however small that may be in the case of elementary particles.

Some matter has color, but some does not. The gases that make up the air we breathe, for example, do not have any colour unless there is a pollutant in the air.

There are usually said to be four states of matter: solid, liquid, gas and plasma. Most kinds of matter can change from one state to another, but it is still matter in all four states.

A substance that can dissolve in another substance is said to be soluble in that material. For example, salt is soluble in water, but gold is not.

Answer: An atom of gold

An atom is the smallest part of an element retaining its properties. Since gold is an element, an atom of gold is the smallest particle with its characteristics. Of course, many of these are not measurable until you have a large number of gold atoms gathered together. That might be called a granule of gold. A granule can display some properties such as malleability which are not seen in a single atom, but the individual atom has the potential to display those properties.

Gold is a metal, so does not form molecules. Electrons are sub-atomic particles which are found inside gold (and all other) atoms.

Answer: 39

The mass number of an atom is equal to the sum of the number of protons and neutrons. In this case, 19 + 20 = 39.

The mass of the electrons is so much smaller than that of the nuclear particles that they are ignored. It is relevant that the number of electrons is equal to the number of protons - this is a neutral atom of potassium, not the ion it forms in reactions by losing an electron. The K+ ion has 18 electrons.

The number of protons in an atom determines its atomic number. All atoms of a given element have the same number of protons.

While all atoms of potassium have 19 protons, they do not all have 20 neutrons. There are some atoms, called isotopes, that have more. While K-39 is the most common one (over 93%), K-41 is about 7% of any sample. this means that the mass of a sample, if carefully measured, is not 39 atomic mass units (amu), but 39.098 amu. (K-40 is highly unstable, so not naturally found.)

Answer: An alloy

An element is a substance all of whose atoms have the same chemical properties, such as oxygen or carbon.

An alloy is a mixture of two elements, at least one of which is a metal; the result is a metal whose properties are not exactly the same as the original one. Familiar alloys include brass (an alloy of copper and zinc), bronze (an alloy of copper and tin) and steel (an alloy of iron and carbon).

A metalloid is an element whose properties are intermediate between the properties of most metals and those of most non-metals. There is no clear definition of the properties of a metalloid, and this is not a formal classification of the elements, just an indication that the dichotomous metal/non-metal classification has problems!

A mineral is a solid material with a fairly well-defined chemical composition and a characteristic crystal structure. Minerals which contain a large amount of metal in their structures are called ores, and are the source for extraction of metals. Hematite, for example is the ore which is most commonly used in the extraction of iron as part of the process of making steel.

Answer: Physical change

Once there was a single piece of paper, now there are two. But it is still paper. The paper is changed physically, not chemically. The chemical substance of the paper is unchanged.

When a chemical changes state (from a solid to a liquid, for example), that is another example of a physical change. The physical properties are different, but the atoms and/or molecules of which it is composed are still the same. This means that the process can be reversed by physical means. Adding heat makes the solid melt, removing heat makes the liquid freeze.

Answer: Evaporation

This is an example of a physical change. The liquid water on the clothes absorbs heat from the warm air, and changes from a liquid to a gas; the individual water molecules then float around in the air.

The changes of state we see around us all the time have specific names. A solid changing to a liquid is melting, while the reverse is freezing. Liquid changing to gas is evaporation, and the change from a gas to a liquid is condensation.

Most school texts describe only these three states of matter, and the four relevant transitions between them. However, there is a fourth state of matter: plasma. A plasma resembles a gas whose atoms have lost electrons to become ions mixed with electrons. Neon lights are an example of an artificial plasma; lightning is a natural plasma.

Answer: Sublimation

Most substances go from a solid to a liquid, which then changes to a gas as more energy is put into the material. For some substances, these two changes of state occur at temperatures that are so close to each other that they effectively change directly from a solid to a gas, which is called sublimation. This may be familiar from seeing the use of dry ice (solid carbon dioxide) to produce 'smoke' for dramatic effect. Dry ice is so called because solid carbon dioxide, when used as a cooling agent instead of regular (water) ice, does not leave a wet residue - the gas just dissipates.

Crystallization is the process of forming crystals, meaning that a substance forms a solid whose atoms are held in a rigid form. When a substance is dissolved in water, the atoms/ion/molecules that make it up are constantly moving around. When they collide, they may join to make a larger particle. These then dissolve again, and the substance stays in solution. However, under the appropriate conditions the larger particles form faster than they dissolve, and crystals are formed.

Answer: Oxygen

While chemists consider a number of oxidation-reduction reactions that do not involve oxygen to be classified as combustion reactions, most of the reactions we experience every day are reactions between some fuel and oxygen.

The most common materials used as fuels are organic compounds, which means their molecules include atoms of carbon. Coal, for example is mostly carbon. Because it is formed from the remains of living organisms, it also contains various impurities, but if it were pure coal it would burn to produce carbon dioxide, and no other products. The most common fuels are hydrocarbons, meaning they also contain hydrogen. These burn to produce carbon dioxide and water.

Answer: Dead plant matter

The more plant matter in the water, the less pure it is. Initially, this is a physical impurity, with solid material in the water. After some time it decays, and the end products dissolve into the water, causing chemical impurities.

Sedimentation is a process used to treat water by allowing physical impurities to settle to the bottom of the water storage vessel as a sediment. Sunlight is used to destroy microbes, and oxidation reactions can remove some chemical impurities.

Answer: Distillation

Since the seawater has been described as clean, there is no need for filtration, which would remove undissolved substances. Chlorination and oxidation will both improve the quality of the water, but the real problem is the dissolved salt, which will still be there.

Distillation is the process of boiling water and collecting the steam, which is then allowed to cool and condense into liquid water. The dissolved salt is left behind in the original container.