Quarks are the building blocks of protons and neutrons, which in turn make up the nuclei of atoms. Think of quarks as the LEGO bricks that snap together to build the world around us. They are fundamental particles, meaning they have no known sub‑structure.
In physics notation we write a quark as \$q\$. Each quark carries a colour charge (red, green, or blue) and a flavour (type).
| Flavour | Symbol | Typical Mass (MeV/\$c^2\$) | Charge (\$e\$) |
|---|---|---|---|
| Up | \$u\$ | 2.2 | \$+\frac{2}{3}\$ |
| Down | \$d\$ | 4.7 | \$-\frac{1}{3}\$ |
| Strange | \$s\$ | 96 | \$-\frac{1}{3}\$ |
| Charm | \$c\$ | 1270 | \$+\frac{2}{3}\$ |
| Bottom | \$b\$ | 4180 | \$-\frac{1}{3}\$ |
| Top | \$t\$ | 173100 | \$+\frac{2}{3}\$ |
Protons are made of two up quarks and one down quark: \$uud\$. Neutrons are one up and two down quarks: \$udd\$. The rule is that the sum of the charges must equal the particle’s charge.
Example: A proton’s charge is +1. Using the quark charges:
Imagine a pizza place that offers six different toppings (flavours). Each topping gives the pizza a unique taste, just as each quark flavour gives a particle a unique identity. The “colour” of a quark is like the pizza’s crust colour – you need all three colours (red, green, blue) together to make a stable particle, just as you need the right combination of toppings to create a delicious pizza.