Hey, reader! My name is Ratmir, and welcome to another post on my chemistry blog! Today’s topic is metals: what they are, their reactions with water and acids, and alloys. With that said, let’s start!

Metals

Metals are defined as chemical elements or alloys that, when polished are shiny, electrically and thermally conductive and are malleable and ductile. Malleable means hammerable (into sheets) without breaking or denting, and ductile essentially means stretchable (into wires). They tend to be solid at room temperature and hard and strong, but there are exceptions, such as:

• Mercury (Hg) – which is liquid at room temperature;
• Alkali metals – which are so soft you can dent them with your fingernail;
• Gallium (Ga) – which isn’t a good electrical conductor (compared to other metals);

Alkali Metals

Because metals are mostly located to the left of the periodic table, they tend to be more basic (alkaline) than non-metals, meaning they have a higher pH. However, a lot of metal oxides actually tend to be rather acidic because of oxygen’s slight acidity cream.

The group of metals located in the first group (column) of the periodic table are the most basic, also called the Alkali Metals. They are the most reactive out of all and so have to be stored in oil to prevent oxidation.

Reactivity Series

An important part of metals are their reactions with different substances. If you arrange all the metals by their rate of reactivity with hydrogen compounds, you can predict the rate of the reaction of the metal when it is placed in a solution of, for example, water (that contains hydrogen). The reaction of metals with these hydrogen compounds are displacement reactions, also called exchange reactions, which are reactions displacing individual elements from compounds, which, in our case, is hydrogen, escaping in the form of gas.

If a metal in the series is less reactive than the element above it, it cannot displace it in a reaction or will do so very slowly. For example, copper won’t react when dropped in acid or water, because it cannot displace the hydrogen and so no reaction will occur.

Reactions with Water and Acids

With the reactivity rates known, metals above the “hydrogen” mark will react with water and acids in a displacement reaction forming hydrogen gas and the metal compound.

When a metal reacts with water, it releases hydrogen and metal hydroxide. For example, lithium dropped in water will release hydrogen and lithium hydroxide.

The typical symbol equation for the reaction of metals and water is:
2Na + 2H₂O -> 2NaOH + H₂ (where Na is any reactive metal)

When a metal reacts with acid, it releases hydrogen and metal salt, which is a compound of the metal and dehydrated acid.

Here is the list of names of salts formed by different acids:

• Hydrochloric acid (HCl) forms chloride salts (Cl₂)
• Sulfuric acid (H₂SO₄) forms sulfate salts (SO₄)
• Nitric acid (HNO₃) forms nitrate salts
• Carbonic acid (H₂CO₃) forms carbonate salts
• Acetic acid (CH₃COOH) forms acetate salts

In terms of symbol equations:
Na + 2HCl -> NaCl₂ + H₂ | Na is any reactive metal
Mg + H₂SO₄ -> MgSO₄ + H₂ | Mg is any reactive metal

Keep in mind, however, that aluminium reacts a bit differently, with the equation:
2Al + 6HCl -> 2AlCl₃ + 3H₂

Alloys

Much more typical in real life than pure metals are alloys. Alloys are mixtures of elements where at least one is a metal. This is done because alloys have the combined “good” properties of both metals. For example, aluminium is a metal that’s very light but weak. Titanium is very strong but heavy. An alloy of the two metals would result in a strong and light material, more useful than the pure metals it’s made of.

Some common alloys include:

• Steel: Iron & Carbon
• Stainless steel: Iron, Chromium & Carbon
• Bronze: Copper & Tin
• Brass: Copper & Zinc

The reasons why alloys have combined properties is because during the creation of an alloy, the uniform grid-like structure of the metal remains the same except its composition. It can change in two ways, forming either a substitutional alloy or an interstitial alloy.

In a substitutional alloy, some of the metal atoms get replaced with atoms of the other element. This causes the new material to have properties of both the metal and the other element.

In an interstitial alloy, since the atoms of the other element are smaller, they fit in between the space between the metal atoms, taking up space for movement which results in the metal being harder and stronger.

Further reading

This post comes to an end, but I highly encourage you to keep on learning! Here are some resources (it’s also what I used as sources for this post):

• Metal – Wikipedia
• Alloy – Wikipedia

Thank you for reading, and I’ll see you in my next post!