Ernest Rutherford

Who Found the Atom Was Nearly Empty · Physicist · 1871–1937

The loud New Zealand farm boy who sorted the radiations into alpha and beta, proved that one element really does turn into another, and discovered that the atom is almost entirely empty space around a tiny nucleus.

Who was Rutherford?

Ernest Rutherford was born in 1871 on a flax farm in Nelson, the fourth of twelve children, and left New Zealand on a scholarship he won as a runner-up. At McGill in Montreal, with the chemist Frederick Soddy, he established that radioactivity is a transmutation — atoms of one element decaying into another — which sounded like alchemy and was nonetheless true, and he introduced the idea of half-life to describe its rate. He sorted the emissions into two kinds and named them alpha and beta, later showing that alpha particles are helium nuclei. Moving to Manchester, he set Hans Geiger and the undergraduate Ernest Marsden to fire alpha particles at a thin sheet of gold foil and count the flashes. Almost all went straight through, but roughly one in eight thousand came back towards the source. Nothing in the accepted model of the atom, a diffuse sphere of positive charge, could do that. The only explanation was a minute, dense, positively charged centre with the atom essentially empty around it: the nucleus. In 1917 he split the nitrogen nucleus with alpha particles, the first artificial transmutation of an element. He won the Nobel Prize in Chemistry, which he found permanently funny, and he trained a generation including Bohr, Chadwick and Blackett. In 1933 he called the prospect of drawing usable energy from the atom 'moonshine'; he died in 1937, a year before fission was found.

Major achievements

• Named and distinguished alpha and beta radiation, and identified alpha as helium nuclei
• Established with Soddy that radioactive decay transmutes one element into another
• Introduced the concept of half-life
• Interpreted the gold-foil scattering and discovered the atomic nucleus
• Performed the first artificial transmutation, splitting nitrogen in 1917

Life in brief

• 1871 — Born in Nelson: On a flax farm, the fourth of twelve children.
• 1895 — Reaches Cambridge: On a scholarship he won only as a runner-up.
• 1899 — Alpha and beta: Sorts and names the two kinds of radiation.
• 1902 — Transmutation: With Soddy at McGill: decay changes one element into another.
• 1908 — Nobel Prize in Chemistry: Which the physicist found permanently funny.
• 1909 — The gold foil: Geiger and Marsden find alpha particles bouncing back.
• 1911 — The nucleus: The atom is almost entirely empty around a tiny dense centre.
• 1917 — Splits nitrogen: The first artificial transmutation of an element.

Explore the life of Rutherford — five chapters

1. The Runner-Up — A flax farm, twelve children, and a scholarship by default
2. Atoms That Turn Into Other Atoms — Montreal, and a word they were afraid to use
3. One in Eight Thousand — Manchester, and a result nothing could explain
4. Splitting Nitrogen — The first artificial transmutation, done during a war
5. Moonshine — 1933, and a prediction that failed within six years

Read the five-chapter life of Ernest Rutherford →

Where Rutherford appears in your course

Ernest Rutherford has a genuine claim on 4 lessons of the Pearson Edexcel International GCSE science course built into Incandio:

• Atomic Structure and Isotopes — Physics: Statement 7.2 is his discovery, and the way it was made is the most instructive experiment on the specification. Geiger and Marsden fired alpha particles at gold foil so thin it was only a few hundred atoms thick, and counted the flashes as they arrived. Almost everything went straight through, which was expected. About one in eight thousand came back towards the source, which was not — and on the accepted model of the atom, a diffuse sphere of positive charge, it was impossible. Rutherford is the right person to ask how you reason from a handful of improbable events to a structure nobody had imagined, and how long it took him to believe it.
• Nuclear Equations — Physics: Every equation on this page says an element becomes a different element, and that claim was genuinely shocking when Rutherford and Frederick Soddy made it at McGill in 1902. Elements were supposed to be the fixed, unchangeable foundations of chemistry, and turning one into another was the discredited goal of the alchemists. Soddy's reaction on realising what their data meant was to say 'Rutherford, this is transmutation', and Rutherford's reply was that for heaven's sake they should not call it that, or they would be thrown out as alchemists. He is the right person to ask what it takes to publish a result that sounds like a discredited idea.
• Detecting Radiation and Background — Physics: Before the Geiger–Müller tube, single alpha particles were detected by letting them strike a zinc sulphide screen and counting the faint flashes through a microscope, by eye, in a completely darkened room after half an hour of letting the eyes adjust. Observers could manage only a few minutes at a time before their counting became unreliable. Hans Geiger did enormous amounts of this in Rutherford's laboratory, and his later development of an electrical counter was a direct response to how bad a detector a tired human being is. Rutherford is the person to ask how you trust a measurement whose instrument is somebody's eye.
• Half-Life — Physics: Half-life is Rutherford's concept, arrived at while he and Soddy were working on thorium at McGill. The striking thing is what it let them do: because each isotope has its own fixed halving time, the rate at which an unknown substance decayed became a way of IDENTIFYING it — a fingerprint that no chemical test could give. That is how the decay chains were untangled, one characteristic time at a time. He is the right person to ask why a quantity describing something entirely unpredictable turns out to be one of the most reliable numbers in physics.

Begin

• Start a conversation with Rutherford — a dramatised, historically grounded AI portrayal
• Read the Historical Brief
• Explore the life of Rutherford — five chapters
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