1Calcium carbide
Reacts with water to produce acetylene gas.
2What is used by cavers and miners as lamps?
Calcium carbide.
3Strontium and nuclear fallout
Strontium is a product of U-235 fission and can replace calcium in bones, leading to cancer.
4Why is strontium dangerous?
It substitutes for calcium in bones and has no biological function.
5Barium sulfate and X-rays
Barium strongly absorbs X-rays and is used as a contrast agent.
6Why is BaSO₄ safe for medical imaging?
It is highly insoluble and cannot be absorbed by the body.
7Radium and radioactivity
Radium glows in the dark and was historically used on watch dials.
8Why did workers painting radium on watches suffer health issues?
They ingested radioactive radium, causing radiation disease.
9Gallium's melting point
Gallium has an unusual melting trend due to intermolecular forces.
10What is a fun property of gallium?
It melts in your hand.
11Oxidation states of Group 13
Al is only +3, while Ga, In, and Tl can be +3 or lower.
12Why is GaCl₂ unusual?
It contains a mix of Ga(I) and Ga(III) oxidation states.
13Boron bonding
Boron prefers polar covalent bonding and forms stable B₁₂ icosahedra.
14Where is boron commonly found?
In borax (Na₂B₄O₇·10H₂O).
15Main use of boron
Borosilicate glass, which has a low thermal expansion coefficient.
16Why is Pyrex better than regular glass?
It expands less with heat due to boron content.
17Boranes
Compounds of boron and hydrogen with unique bonding.
18What type of bonding do boranes have?
A mix of 2c-2e and 3c-2e bonds.
19Aluminum reactivity
Reacts with both acids and bases.
20Why shouldn't pure aluminum cookware be used with acidic food?
It reacts with acid, affecting food and degrading the metal.
21Aluminum recycling
Lightweight, strong, and highly recyclable.
22Why does aluminum resist rusting?
It forms a protective Al₂O₃ layer.
23Anodized aluminum
Has an enhanced oxide coating for protection.
24What is a common use of anodized aluminum?
Cookware.