ACTINIDES: RADIOACTIVE RARE EARTHS

Actinides Overview

Also known as: Actinide series, radioactive rare earths

Elements: Actinium (Ac), Thorium (Th), Protactinium (Pa), Uranium (U), Neptunium (Np), Plutonium (Pu), Americium (Am), Curium (Cm), Berkelium (Bk), Californium (Cf), Einsteinium (Es), Fermium (Fm), Mendelevium (Md), Nobelium (No), Lawrencium (Lr)

Common Properties: All are radioactive, f-block elements, form +3 oxidation state, similar chemical properties to lanthanides

Actinium

Radioactive

Atomic Number89

Atomic Mass227 u

Electron Config[Rn] 6d¹ 7s²

Common IonsAc³⁺

Melting Point1050°C

Density10.07 g/cm³

Actinium glows with an eerie blue light in the dark due to its radioactivity - it's 150 times more radioactive than radium!

Properties: Silvery-white, radioactive, glows blue in dark

Applications: Neutron sources, cancer treatment, scientific research

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Thorium

Nuclear Fuel

Atomic Number90

Atomic Mass232.04 u

Electron Config[Rn] 6d² 7s²

Common IonsTh⁴⁺

Melting Point1750°C

Density11.7 g/cm³

Thorium is 3 times more abundant than uranium and could power the world for thousands of years with safer nuclear reactors!

Properties: Silvery, radioactive, paramagnetic, ductile

Applications: Nuclear fuel, aircraft engines, welding rods

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Protactinium

Highly Toxic

Atomic Number91

Atomic Mass231.04 u

Electron Config[Rn] 5f² 6d¹ 7s²

Common IonsPa⁴⁺, Pa⁵⁺

Melting Point1572°C

Density15.4 g/cm³

Protactinium is one of the rarest and most expensive naturally occurring elements - it took 60,000 times more effort to isolate than radium!

Properties: Silvery, radioactive, highly toxic

Applications: Scientific research, geological dating

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Uranium

Nuclear Power

Atomic Number92

Atomic Mass238.03 u

Electron Config[Rn] 5f³ 6d¹ 7s²

Common IonsU³⁺, U⁴⁺, U⁶⁺

Melting Point1132°C

Density19.1 g/cm³

Uranium is 40 times more abundant than silver in Earth's crust and was used to create the first atomic bombs and nuclear reactors!

Properties: Silvery, radioactive, dense, paramagnetic

Applications: Nuclear power, nuclear weapons, radiation shielding

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Neptunium

Synthetic

Atomic Number93

Atomic Mass237 u

Electron Config[Rn] 5f⁴ 6d¹ 7s²

Common IonsNp³⁺, Np⁴⁺, Np⁵⁺, Np⁶⁺, Np⁷⁺

Melting Point644°C

Density20.2 g/cm³

Neptunium was the first synthetic transuranium element discovered and is named after the planet Neptune, following uranium's naming after Uranus!

Properties: Silvery, radioactive, paramagnetic

Applications: Neutron detection, scientific research

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Plutonium

Weapons Grade

Atomic Number94

Atomic Mass244 u

Electron Config[Rn] 5f⁶ 7s²

Common IonsPu³⁺, Pu⁴⁺, Pu⁵⁺, Pu⁶⁺

Melting Point640°C

Density19.8 g/cm³

Plutonium is so radioactive that it feels warm to the touch and was used in the "Fat Man" bomb that destroyed Nagasaki in WWII!

Properties: Silvery, radioactive, pyrophoric, warm to touch

Applications: Nuclear weapons, nuclear power, space probes

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Americium

In Your Home

Atomic Number95

Atomic Mass243 u

Electron Config[Rn] 5f⁷ 7s²

Common IonsAm³⁺, Am⁴⁺, Am⁵⁺, Am⁶⁺

Melting Point1176°C

Density12 g/cm³

Americium is in your home right now! It's used in smoke detectors - a tiny amount (0.0000001 grams) can protect an entire house!

Properties: Silvery-white, radioactive, paramagnetic

Applications: Smoke detectors, neutron sources, industrial gauges

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Curium

Glows

Atomic Number96

Atomic Mass247 u

Electron Config[Rn] 5f⁷ 6d¹ 7s²

Common IonsCm³⁺, Cm⁴⁺

Melting Point1340°C

Density13.5 g/cm³

Curium is so radioactive that it glows in the dark with a pale purple light and was named after Marie and Pierre Curie, the pioneers of radioactivity!

Properties: Silvery, radioactive, glows in dark

Applications: Spacecraft power sources, scientific research

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Berkelium

Synthetic

Atomic Number97

Atomic Mass247 u

Electron Config[Rn] 5f⁹ 7s²

Common IonsBk³⁺, Bk⁴⁺

Melting Point986°C

Density14.8 g/cm³

Berkelium was the first element produced in weighable quantities that doesn't occur naturally on Earth, and it's named after Berkeley, California where it was discovered!

Properties: Silvery, radioactive, tarnishes in air

Applications: Scientific research, production of heavier elements

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Californium

Expensive

Atomic Number98

Atomic Mass251 u

Electron Config[Rn] 5f¹⁰ 7s²

Common IonsCf³⁺, Cf⁴⁺

Melting Point900°C

Density15.1 g/cm³

Californium is one of the most expensive elements - it costs about $27 million per gram and is an incredibly powerful neutron source!

Properties: Silvery, radioactive, highly neutron-emitting

Applications: Neutron source, cancer treatment, metal detection

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Einsteinium

Synthetic

Atomic Number99

Atomic Mass252 u

Electron Config[Rn] 5f¹¹ 7s²

Common IonsEs³⁺

Melting Point860°C

Density8.84 g/cm³

Einsteinium was discovered in the fallout from the first hydrogen bomb test in 1952 and is named after Albert Einstein!

Properties: Silvery, radioactive, soft metal

Applications: Scientific research, production of mendelevium

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Fermium

Synthetic

Atomic Number100

Atomic Mass257 u

Electron Config[Rn] 5f¹² 7s²

Common IonsFm³⁺

Melting Point1527°C

DensityUnknown

Fermium was also discovered in hydrogen bomb fallout and is named after Enrico Fermi, the creator of the world's first nuclear reactor!

Properties: Radioactive, synthetic, extremely rare

Applications: Scientific research only

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Mendelevium

Synthetic

Atomic Number101

Atomic Mass258 u

Electron Config[Rn] 5f¹³ 7s²

Common IonsMd²⁺, Md³⁺

Melting Point827°C

DensityUnknown

Mendelevium was the first element to be synthesized one atom at a time and is named after Dmitri Mendeleev, who created the periodic table!

Properties: Radioactive, synthetic, extremely unstable

Applications: Scientific research only

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Nobelium

Synthetic

Atomic Number102

Atomic Mass259 u

Electron Config[Rn] 5f¹⁴ 7s²

Common IonsNo²⁺, No³⁺

Melting Point827°C

DensityUnknown

Nobelium is named after Alfred Nobel, the inventor of dynamite and founder of the Nobel Prizes!

Properties: Radioactive, synthetic, extremely unstable

Applications: Scientific research only

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Lawrencium

Synthetic

Atomic Number103

Atomic Mass262 u

Electron Config[Rn] 5f¹⁴ 6d¹ 7s²

Common IonsLr³⁺

Melting Point1627°C

DensityUnknown

Lawrencium is the last actinide and is named after Ernest O. Lawrence, inventor of the cyclotron particle accelerator!

Properties: Radioactive, synthetic, extremely unstable

Applications: Scientific research only

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