Chemistry★ Legendary
Gold
Guld
Discovered 4500 BC · Varna, BulgariaEUREKA 08
Gold★
The ideaGold is a noble metal: it hardly reacts, so it never rusts and stays shiny for thousands of years.
Au · atomic number 79 · ρ = 19.3 g/cm³
Lets you predictTreasure found after 3,000 years still shines.
Tests usually ask
- Reactivity: why gold does not rust
- Carats as percent
Scan for the full explanation and a practice question.
Eureka · 08/10
Eureka · 08/10
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Chemistry ★ Legendary: one of the biggest ideas in science
Gold
Swedish: Guld · Discovered: Oldest known gold jewellery: Varna, Bulgaria, about 4500 BC · symbol from Latin aurum
Gold is a noble metal: it hardly reacts, so it never rusts and stays shiny for thousands of years.
Au · atomic number 79 · ρ = 19.3 g/cm³
Why it works
Legendary card because gold is rare: only about 4 grams in every 1,000 tonnes of Earth's crust.
Pure gold is 24 carat. An 18 carat ring is 18/24 = 75 % gold, mixed with other metals to make it harder.
What it lets you predict
Treasure found after 3,000 years still shines.
How tests ask about it
- Reactivity: why gold does not rust
- Carats as percent
Try it
An 18 carat ring weighs 10 g. How much of it is gold?
Show the answer
18 / 24 = 0.75, so 0.75 × 10 = 7.5 g of gold.
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