Chemical Properties of Matter
Written by tutor Andrew L.
What do you mean property of matter...?
Contrary to what it sounds like, matter does not own any property. Instead, properties of matter refer to any characteristic that we observe about a substance that can be used to distinguish it from other substances. There are two main types of properties of matter, physical properties and chemical properties.
Think about every time we go out and see hundreds maybe thousands of people each day. Now, imagine we couldn’t identify any differences between them. Every person was a female with brown hair, blue eyes, 5 foot 3 inches, laughed at the same jokes, enjoyed the same movies, and even had the same name, Sandy. How would you tell Sandy and Sandy apart?
You can’t! We would have a lot of identity theft and the world would certainly be boring. Luckily, people have determined a way to use their 5 senses to tell individuals apart. Everything, from hair color, height, clothing, and even the way we smell, can be used differentiate each person apart from one another. All of these different characteristics we inherently possess are considered properties, combine a bunch of different properties together and BOOM we have a unique individual, YOU!
Physical vs. Chemical Properties
Matter can be uniquely identified by using two main categories of properties, they are physical and chemical. Physical properties of matter refer to characteristics of a substance that can be observed WITHOUT changing the actual “makeup” of a substance. Some physical properties include mass, volume, color, boiling point, how hard a substance is, and even taste. Many things that we come in contact with can be accurately identified by just using some physical properties that we observe about it. For example, when we see a red octagon with white letters spelling “S-T-O-P” we automatically know it’s a stop sign and we should probably stop if we don’t want a ticket. Not many people need to get out of their car, rip out a bottle of hydrochloric acid, sprinkle some on the sign, and observe the chemical effects of a strong acid with a stop sign.
On the other hand if we see a white, fluffy substance we can obviously assume it’s a pillow, right? Wrong! If you said pillow, that is a possibility, but if you said cloud you’re also right, even if you said your grandma’s dog, you could also be right. This presents a problem, a big problem.
So what is a Chemical Property?
Chemical properties are observable characteristics of the makeup of a substance. Observable does not necessarily mean that one can visually see it; rather it means that we can note the result. We can observe a smell, a voltage, or even a time.
In the prior case, we saw a white, fluffy substance. We did some more testing and observed that upon addition of an aldehyde to the substance we were left with a hydrate. In organic chemistry we learn that aldehydes mix with water to produce hydrates. Because of this we can assume that the white, fluffy thing is made of water vapor and the substance is probably a cloud.
More about Chemical Properties
Now that we have an idea of what properties are and how they are broken up into physical and chemical components. Let’s talk about some well-known chemical properties and how they identify the substance that they represent. Remember, the more properties we know about a substance the more we can differentiate that substance from other substances.
How many times have you been out where your friend asks you, "Dude what’s that shiny, silvery thing over there?" I know, not many times for me either. Well, we pick it up and it’s a silver necklace, at least we think it is. It’s reflective, silver, and taste like metal. But we want to be sure, so we look up some chemical properties of silver.
“Chemical properties are observable characteristics of the makeup of a substance”
We find out that Silver (Ag) reacts with elemental Oxygen (O2) to form Silver Oxide Ag2O. If this necklace were actually plated with silver instead of being made out of silver we would expect a different result than what we observe with pure silver. One element that we have an abundance of in our atmosphere is Oxygen (O2), so we could do a lot of tests it. We leave the necklace in a bottle and fill it with pure O2. After some time, we see that the necklace has reacted. We take out the necklace and analyze the chemical composition of the result; we find that we have a good amount of Silver Oxide (Ag2O) present. Great, chemical properties have helped us solve the mystery of the shiny necklace, but too bad we no longer have our necklace. That’s a main point that I should tell you, in the process of observing chemical properties we often must alter the chemical composition of the original substance to obtain the property. With this said, make sure not to go and react your mom’s necklace without letting her know, because the reaction is often irreversible!
Chemical properties and the periodic table
Now that we learned what chemical properties are, let’s get back to basics “The Periodic Table of Elements.” Of course there are many ways that we can classify these elements, we can classify them according to size, color, smell, behavior, or even by the way they react with water.
Chemists have determined that the best way to organize the elements is to align them into vertical columns (“groups” or “families”) and then to further classify them into regions based on their behavior.
Let’s start off by exploring the families of the periodic table:
Group 1A: Alkali Metals (Li, Na, K, Rb, Cs, Fr)
All of these elements are metals and exist as solids at room temperature. These elements are extremely reactive, due to their valence shell containing only 1 electron. They all react with water to produce hydrogen and alkaline solutions. In case you’re wondering, alkaline solutions are mixtures of a basic solid dissolved in water. Being that these elements absolutely hate being alone, we always find these elements reacted with another element in nature. An example of this is sodium chloride (NaCl).
Group 2A: Alkaline Earth Metals (Be, Mg, Ca, Sr, Ba, Ra)
Just like Group 1A metals, these elements (with the exception of Be) react with water to produce alkaline solutions. Many times these elements are found as their cousin oxides, such as Calcium Oxide (CaO), in which case they still react with water to produce alkaline solutions. Magnesium and Calcium are the earth’s seventh and fifth most abundant crust constituent. No wonder they are called “earth metals”.
Group 3A: (B, Al, Ga, In, Tl)
The main similarity of these elements is that they all form compounds with analogous formulas. What does that mean? Well if we take Boron (B) and mix it with abundance with Chloride (Cl), we end up with BCl3. Ok, I agree, not too interesting; but, what if we take another element of group 3A...how about Aluminum (Al). If Aluminum is mixed with an abundance of Chloride we get (drumroll please) AlCl3. This is pretty extraordinary, so because of this we can claim they are all a family and react similarly.
Group 4A: (C, Si, Ge, Sn, Pb)
Starting with this group and moving to the right, we start to see more and more nonmetals present in each family. In this family, Carbon (C) is a nonmetal, Silicon (Si) and Germanium (Ge) are metalloids, Tin (Sn) and lead (Pb) are metals. It becomes apparent that families are becoming more diverse moving to the right. Since this family, 4A, happens to be very diverse, more variation occurs in the properties of this group. Just as in group 3A, all of these elements happen to form similar compounds such as CO2, SiO2, GeO2, SnO2, and PbO2.
Group 5A: (N, P, As, Sb, Bi)
Again, we see a metal mixed with a nonmetal and a metalloid in this family...it appears that there probably won’t be that many properties that these elements share. It turns out that these elements are grouped together because they all form similar compounds. An example is in the case of Oxides, N2O5, P2O5, and As2O5.
Group 6A: (O, S, Se, Te, Po)
Like our families at home, group 6A is a very diverse family of elements. These elements don’t have a whole lot in common, but then again what do you really have in common with your parents?. All elements in group 6A form similar Oxygen containing compounds SO2, SeO2, and TeO2. Interestingly, they all form similar sodium containing compounds as well, Na2O, Na2S, Na2Se, and Na2Te.
Group 7A: Halogens (F, Cl, Br, I, At)
This entire group is formed of nonmetals indicating that we are likely to find a lot of similarities within this family. All of the halogens exist as diatomic molecules in nature, are extremely reactive (the most reactive of all the elements, in fact), and they all react extremely violent with the alkali metals to form salts. Enjoy your table salt (NaCl) because sodium reacted pretty violently with Chloride to form this.
Group 8A: Noble Gases (He, Ne, Ar, Kr, Xe, Rn)
The good old noble gases! Where would we be today without some helium balloons for your birthday or no neon light up signs? All of these gases are extremely rare on earth and therefore were not discovered until late 19th century. These elements absolutely hate to react with other elements. They prefer to be as isolated as possible because, after all, they are noble.
Groups 1B-8B: Transition Metals
All of these elements are metals, hence the name transition metals. It’s hard to find similar properties in these groups so we will leave them alone for now. The main classification that all these elements share is their unfilled d-subshell. We didn’t talk too much about quantum numbers, but you will soon see how valence shells can affect the behavior of elements and how they react.
So let’s all give a round of applause for Dmitri Ivanovitch Mendeleev and his organization of the modern day Periodic Table of Elements. Mendeleev saw that elements possess similar characteristics (properties) if looked at by a function of their atomic number. This became known as “The law of chemical periodicity” it’s pretty obvious why. This law states that the properties of elements are functions of the atomic number of the element, WOW! Even more interesting, a lot of the elements were not even discovered when he made the first periodic table of elements, so he actually left spots in his original table for “possible elements” that he believed would be discovered in the future. Now that’s cool!
Some more interesting chemical properties
It turns out that chemistry is filled with tons and tons of chemical properties. Some properties are shared between substances and some are not. It turns out that there are so many different chemical compositions in our universe that it would be impossible to approach each separately. Luckily for us, chemists have taken individual compounds and grouped them into different classes that each share similar chemical properties.
Let’s talk about a few:
An alcohol is any organic compound that contains a hydroxyl group attached to a carbon. As you can imagine, there is a huge number of ways that one can attach a hydroxyl group to a carbon atom. There are so many ways that chemists realized, it’s probably smarter to just classify them all as types of alcohols.
All alcohols share some common chemical properties, for instance upon reacting an alcohol with O2 (also known as a combustion reaction) we will always get carbon dioxide (CO2) and water (H2O).
Another interesting property is alcohol’s ability to be oxidized. Alcohols can be oxidized into carboxylic acids with the usage of oxidizing agents such as potassium dichromate (VI) or potassium manganite (VII). By the way, this is the reason wine turns sour if left in the presence of oxygen.
We can go on and on about the chemical properties of various classes, but the main point of this article is to get you acquainted to what a chemical property is.
What’s the big idea?
So what? I know what a chemical property is, how does that help me? Well, just like identifying your friends by their respective names, just like being able to tell the difference between day and night, and just like being able to differentiate between hot and cold, as maturing chemists we need the ability to identify a substance and set it apart from every other substance in the universe! We can’t go around claiming ethanol is the same as water just because they share the same property of color. We can’t breathe in carbon monoxide (CO) instead of Oxygen (O2) because they both are odorless. The more chemical properties we know about a certain type of matter, the better we can differentiate that substance from every other substance in our universe!
Chemical Properties Practice Quiz
Choose the answer with the correct coefficients. If the coefficient is 1, there will be a 1 present in the answer choice.
Which of the following is a chemical property?
Why do we identify substances by their properties?
How can we tell the difference between water and ethanol?
What is the definition of chemical periodicity?
Which of the following would react with water to form hydrogen and alkaline solution?