sodium

Everyday

1. Sodium is a soft, silvery-white metal element with the symbol Na; it is so reactive that it reacts strongly with water, sometimes fizzing and catching fire, so it is never found pure in nature. tree →
2. Sodium is part of many compounds, most famously sodium chloride, which is common table salt; «sodium» on a food label usually means salt in the food. tree →

In the lessons

In science lessons sodium is in the periodic table among the alkali metals; teachers show a tiny piece fizzing across water behind a safety screen. In health and food lessons, food labels list sodium or salt, and eating too much can raise blood pressure. Street lights used to glow orange because they used sodium vapour. Phrases: sodium chloride, sodium bicarbonate (baking soda), low sodium, sodium lights.

Examples

• Table salt is made of sodium and chlorine. tree →
• Sodium is so soft you can cut it with a knife. tree →
• The teacher dropped a tiny piece of sodium into water and it whizzed around. tree →
• Too much sodium in food is not good for your heart. tree →
• The label shows how much sodium is in the crisps. tree →
• Old orange street lights were sodium lamps. tree →
• Sodium bicarbonate makes cakes rise. tree →
• The symbol for sodium is Na, from its Latin name «natrium». tree →

Note

Uncountable: «too much sodium», not «a sodium». Pronounced «SOH-dee-um». Symbol trap: sodium is Na, not So or S (S is sulphur). Safety: pure sodium is dangerous and only used by teachers or scientists. On food labels in some countries, the salt amount is about two and a half times the sodium amount.