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Learning what happens when an atom gains or loses electrons to become electrically charged.
Have you ever wondered why salt crystals stick together so perfectly, or why a battery can power your phone? It all starts when atoms stop being 'neutral' and start getting an attitude!
In their normal state, atoms are like a perfectly balanced scale. They have the same number of protons (which have a charge) and electrons (which have a charge). Because the positives and negatives match exactly, the atom is neutral, meaning its total charge is zero. However, atoms aren't always happy being neutral. They are constantly looking for ways to become more 'stable,' and often, that means changing the number of electrons they carry. When an atom gains or loses an electron, it becomes an ion—an atom with a net electrical charge.
Quick Check
If an atom has 3 protons and 3 electrons, what is its total electrical charge?
Answer
Zero (or Neutral)
When an atom changes its electron count, it takes on a specific identity. If an atom loses electrons, it now has more positive protons than negative electrons. This creates a positive ion called a cation. A great way to remember this is that the word 'cation' has a 't' in it that looks like a plus sign (), or remember that 'cats' have 'paws' (it's paws-itive!). On the flip side, if an atom gains electrons, it becomes a negative ion called an anion. Think of an 'anion' as 'A Negative Ion.'
Let's look at a Sodium () atom. 1. A neutral Sodium atom has protons and electrons. 2. If it loses electron, it now has protons and electrons. 3. Using the math: . 4. Sodium is now a cation with a charge of , written as .
Quick Check
If an Oxygen atom gains 2 electrons, does it become a cation or an anion?
Answer
Anion
Oxygen () has protons. To become stable, it wants to have total electrons. 1. Start with protons: . 2. Add the electrons it wants: . 3. Calculate: . 4. Oxygen becomes an anion with a charge of , written as .
Magnesium () has protons and electrons. Its electron configuration is . To reach a stable 'Octet' (8), it is much easier to lose the outer electrons than to find more. 1. Protons stay the same: . 2. New electron count after losing 2: . 3. Math: . 4. The resulting ion is .
Which of the following describes a Cation?
If an ion has 17 protons and 18 electrons, what is its charge?
Atoms change their number of protons to become ions.
Review Tomorrow
In 24 hours, try to explain to a friend the difference between a cation and an anion using the 'paws-itive' cat analogy.
Practice Activity
Look at a Periodic Table and find Aluminum (Atomic number 13). If it loses 3 electrons to become stable, calculate its charge and decide if it is a cation or an anion.