Lesson 02 · Meet the elements
Start small.
Meet the first twenty.
From hydrogen to calcium: a manageable set of names, symbols and positions to help you feel at home on the periodic table.
One element, one proton count.
The first 20 elements have atomic numbers 1–20. That number counts protons in the nucleus. The letters are the element’s chemical symbol.
Select an element. Columns are groups; rows are periods.
Groups 3–12 are omitted here: none of the first 20 elements occupy them. Period 4 continues beyond this subset.
Hydrogen
Atomic number 1 · Group 1 · Period 1
Read the complete names and symbols list
| Number | Symbol | Name |
|---|---|---|
| 1 | H | Hydrogen |
| 2 | He | Helium |
| 3 | Li | Lithium |
| 4 | Be | Beryllium |
| 5 | B | Boron |
| 6 | C | Carbon |
| 7 | N | Nitrogen |
| 8 | O | Oxygen |
| 9 | F | Fluorine |
| 10 | Ne | Neon |
| 11 | Na | Sodium |
| 12 | Mg | Magnesium |
| 13 | Al | Aluminium |
| 14 | Si | Silicon |
| 15 | P | Phosphorus |
| 16 | S | Sulfur |
| 17 | Cl | Chlorine |
| 18 | Ar | Argon |
| 19 | K | Potassium |
| 20 | Ca | Calcium |
Learn a name and its symbol together.
The first letter is uppercase; a second letter is lowercase. Write He for helium and Cl for chlorine. The casing is part of the symbol.
Na → Sodium
Na comes from the name natrium. S is already the symbol for sulfur.
K → Potassium
K comes from kalium. P is the symbol for phosphorus.
Try four small sets
Read five name–symbol pairs, hide the list, then write what you remember. Check the missing pairs before adding the next set.
- 1–5: H, He, Li, Be, B
- 6–10: C, N, O, F, Ne
- 11–15: Na, Mg, Al, Si, P
- 16–20: S, Cl, Ar, K, Ca
These sets are a study aid, not chemical families. Once the names feel familiar, use the actual rows and columns to find relationships.
Mini self-check: name Na, N and Ne.
Na is sodium, N is nitrogen and Ne is neon. Each symbol identifies a different element.
Notice the patterns, not just the order.
- Li, Na, K: three group 1 alkali metals. Hydrogen sits in group 1 too, but is a nonmetal.
- Be, Mg, Ca: three group 2 alkaline earth metals.
- He, Ne, Ar: noble gases in group 18.
- F and Cl: halogens in group 17.
Read across period 3: Na, Mg, Al, Si, P, S, Cl, Ar. Read down group 2: Be, Mg, Ca. A row and a family tell you different things.
Connect familiar names to real materials
Oxygen gas is part of the air we breathe. Silicon is used in computer chips. Table salt contains sodium and chlorine as ions in a compound; its properties are very different from sodium metal or chlorine gas.
An element and a compound containing that element are not interchangeable. Learning where an element occurs is useful, but does not tell you how its pure form behaves.
Mini self-check: which group links magnesium and calcium?
Group 2. They share a column, but magnesium is in period 3 and calcium in period 4.
Check what stuck.
Three questions on symbols, numbers and groups. You can revisit the lesson at any time.
Question 1 of 3
Which symbol belongs to sodium?
Turn those names into useful clues.
Next, learn to combine an element’s position and properties in a guessing game.
The daily game and Element Challenges include elements beyond the first 20.
Sources & further reading
- American Chemical Society: elements 1–20
- Royal Society of Chemistry: names, symbols, positions and uses
- RSC: sodium and the origin of Na · potassium and the origin of K
Original learning activities and questions by Elemendle.