How many neutrons does zinc 72?

Naturally occurring zinc (Zn) is composed of the 5 stable isotopes 64Zn, 66Zn, 67Zn, 68Zn, and 70Zn with 64Zn being the most abundant (48.6% natural abundance). Twenty-one radioisotopes have been characterised with the most abundant and stable being 65Zn with a half-life of 244.26 days, and 72Zn with a half-life of 46.5 hours. All of the remaining radioactive isotopes have half-lives that are less than 14 hours and the majority of these have half lives that are less than 1 second. This element also has 4 meta states.

Zinc has been proposed as a "salting" material for nuclear weapons (cobalt is another, better-known salting material). A jacket of isotopically enriched 64Zn, irradiated by the intense high-energy neutron flux from an exploding thermonuclear weapon, would transmute into the radioactive isotope Zn-65 with a half-life of 244 days and produce approximately 2.27 MeV of gamma radiation, significantly increasing the radioactivity of the weapon's fallout for several days. Such a weapon is not known to have ever been built, tested, or used.
Standard atomic mass: 65.409(4) u

Table

Notes

• Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
• Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC which use expanded uncertainties.

References

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• Symbol:Zn
• Atomic Number:30
• Atomic Weight:65.38
• Classification:Transition metal
• Phase at Room Temperature:Solid
• Density:7.14 grams per cm cubed
• Melting Point:419°C, 787°F
• Boiling Point:907°C, 1665°F
• Discovered by:Known about since ancient times

For more information on the Visual Elements image see the Uses and properties section below.

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Zinc

Discovery dateIdentified as an element in 1746, but known to the Greeks and Romans before 20BC. Discovered byAndreas Marggraf Origin of the nameThe name is derived from the German, 'zinc', which may in turn be derived from the Persian word 'sing', meaning stone. Allotropes
 

Zn

Zinc

30

65.38  

Glossary

Group
A vertical column in the periodic table. Members of a group typically have similar properties and electron configurations in their outer shell.

Period
A horizontal row in the periodic table. The atomic number of each element increases by one, reading from left to right.

Block
Elements are organised into blocks by the orbital type in which the outer electrons are found. These blocks are named for the characteristic spectra they produce: sharp (s), principal (p), diffuse (d), and fundamental (f).

Atomic number
The number of protons in an atom.

Electron configuration
The arrangements of electrons above the last (closed shell) noble gas.

Melting point
The temperature at which the solid–liquid phase change occurs.

Boiling point
The temperature at which the liquid–gas phase change occurs.

Sublimation
The transition of a substance directly from the solid to the gas phase without passing through a liquid phase.

Density (g cm−3)
Density is the mass of a substance that would fill 1 cm3 at room temperature.

Relative atomic mass
The mass of an atom relative to that of carbon-12. This is approximately the sum of the number of protons and neutrons in the nucleus. Where more than one isotope exists, the value given is the abundance weighted average.

Isotopes
Atoms of the same element with different numbers of neutrons.

CAS number
The Chemical Abstracts Service registry number is a unique identifier of a particular chemical, designed to prevent confusion arising from different languages and naming systems.

Fact box

Fact box

Group12 Melting point419.527°C, 787.149°F, 692.677 K Period4 Boiling point907°C, 1665°F, 1180 K Blockd Density (g cm−3)7.134 Atomic number30 Relative atomic mass65.38  State at 20°CSolid Key isotopes64Zn Electron configuration[Ar] 3d104s2 CAS number7440-66-6 ChemSpider ID22430ChemSpider is a free chemical structure database

Glossary

Image explanation

Murray Robertson is the artist behind the images which make up Visual Elements. This is where the artist explains his interpretation of the element and the science behind the picture.

Appearance

The description of the element in its natural form.

Biological role

The role of the element in humans, animals and plants.

Natural abundance

Where the element is most commonly found in nature, and how it is sourced commercially.

Uses and properties

Uses and properties

Image explanation

An alchemical symbol for zinc is against an abstract background inspired by zinc roofing materials.

Appearance

A silvery-white metal with a blue tinge. It tarnishes in air.

Uses

Most zinc is used to galvanise other metals, such as iron, to prevent rusting. Galvanised steel is used for car bodies, street lamp posts, safety barriers and suspension bridges.

Large quantities of zinc are used to produce die-castings, which are important in the automobile, electrical and hardware industries. Zinc is also used in alloys such as brass, nickel silver and aluminium solder.

Zinc oxide is widely used in the manufacture of very many products such as paints, rubber, cosmetics, pharmaceuticals, plastics, inks, soaps, batteries, textiles and electrical equipment. Zinc sulfide is used in making luminous paints, fluorescent lights and x-ray screens.

Biological role

Zinc is essential for all living things, forming the active site in over 20 metallo-enzymes. The average human body contains about 2.5 grams and takes in about 15 milligrams per day. Some foods have above average levels of zinc, including herring, beef, lamb, sunflower seeds and cheese.

Zinc can be carcinogenic in excess. If freshly formed zinc(II) oxide is inhaled, a disorder called the ‘oxide shakes’ or ‘zinc chills’ can occur.

Natural abundance

Zinc is found in several ores, the principal ones being zinc blende (zinc sulfide) and calamine (zinc silicate). The principal mining areas are in China, Australia and Peru. Commercially, zinc is obtained from its ores by concentrating and roasting the ore, then reducing it to zinc by heating with carbon or by electrolysis. World production is more than 11 million tonnes a year.

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History

History

Elements and Periodic Table History

Zinc was known to the Romans but rarely used. It was first recognised as a metal in its own right in India and the waste from a zinc smelter at Zawar, in Rajasthan, testifies to the large scale on which it was refined during the period 1100 to the 1500.

Zinc refining in China was carried out on a large scale by the 1500s. An East India Company ship which sank off the coast of Sweden in 1745 was carrying a cargo of Chinese zinc and analysis of reclaimed ingots showed them to be almost the pure metal.

In 1668, a Flemish metallurgist, P. Moras de Respour, reported the extraction of metallic zinc from zinc oxide, but as far as Europe was concerned zinc was discovered by the German chemist Andreas Marggraf in 1746, and indeed he was the first to recognise it as a new metal.

Glossary

Atomic radius, non-bonded
Half of the distance between two unbonded atoms of the same element when the electrostatic forces are balanced. These values were determined using several different methods.

Covalent radius
Half of the distance between two atoms within a single covalent bond. Values are given for typical oxidation number and coordination.

Electron affinity
The energy released when an electron is added to the neutral atom and a negative ion is formed.

Electronegativity (Pauling scale)
The tendency of an atom to attract electrons towards itself, expressed on a relative scale.

First ionisation energy
The minimum energy required to remove an electron from a neutral atom in its ground state.

Atomic data

Atomic data

Atomic radius, non-bonded (Å)2.01Covalent radius (Å)1.20Electron affinity (kJ mol−1)Not stableElectronegativity
(Pauling scale)1.65Ionisation energies
(kJ mol−1) 

1st

906.402

2nd

1733.3

3rd

3832.687

4th

5731.2

5th

7969.7

6th

10420

7th

12929

8th

16788

Glossary

Common oxidation states

The oxidation state of an atom is a measure of the degree of oxidation of an atom. It is defined as being the charge that an atom would have if all bonds were ionic. Uncombined elements have an oxidation state of 0. The sum of the oxidation states within a compound or ion must equal the overall charge.

Isotopes

Atoms of the same element with different numbers of neutrons.

Key for isotopes

Oxidation states and isotopes

Oxidation states and isotopes

Common oxidation states2IsotopesIsotopeAtomic massNatural abundance (%)Half lifeMode of decay 64Zn63.92949.17> 7 x 1020 y EC-β+  66Zn65.92627.73- -  67Zn66.9274.04- -  68Zn67.92518.45- -  70Zn69.9250.61> 2.3 x 1016 y β-β- 

Glossary

Data for this section been provided by the British Geological Survey.

Relative supply risk

An integrated supply risk index from 1 (very low risk) to 10 (very high risk). This is calculated by combining the scores for crustal abundance, reserve distribution, production concentration, substitutability, recycling rate and political stability scores.

Crustal abundance (ppm)

The number of atoms of the element per 1 million atoms of the Earth’s crust.

Recycling rate

The percentage of a commodity which is recycled. A higher recycling rate may reduce risk to supply.

Substitutability

The availability of suitable substitutes for a given commodity.
High = substitution not possible or very difficult.
Medium = substitution is possible but there may be an economic and/or performance impact
Low = substitution is possible with little or no economic and/or performance impact

Production concentration

The percentage of an element produced in the top producing country. The higher the value, the larger risk there is to supply.

Reserve distribution

The percentage of the world reserves located in the country with the largest reserves. The higher the value, the larger risk there is to supply.

Political stability of top producer

A percentile rank for the political stability of the top producing country, derived from World Bank governance indicators.

Political stability of top reserve holder

A percentile rank for the political stability of the country with the largest reserves, derived from World Bank governance indicators.

Supply risk

Supply risk

Relative supply risk4.8Crustal abundance (ppm)72Recycling rate (%)>30SubstitutabilityLowProduction concentration (%)30Reserve distribution (%)22Top 3 producers

• 1) China
• 2) Australia
• 3) Peru

• 1) Australia
• 2) China
• 3) Peru

Glossary

Specific heat capacity (J kg−1 K−1)

Specific heat capacity is the amount of energy needed to change the temperature of a kilogram of a substance by 1 K.

Young's modulus

A measure of the stiffness of a substance. It provides a measure of how difficult it is to extend a material, with a value given by the ratio of tensile strength to tensile strain.

Shear modulus

A measure of how difficult it is to deform a material. It is given by the ratio of the shear stress to the shear strain.

Bulk modulus

A measure of how difficult it is to compress a substance. It is given by the ratio of the pressure on a body to the fractional decrease in volume.

Vapour pressure

A measure of the propensity of a substance to evaporate. It is defined as the equilibrium pressure exerted by the gas produced above a substance in a closed system.

Pressure and temperature data – advanced

Pressure and temperature data – advanced

Specific heat capacity
(J kg−1 K−1)388Young's modulus (GPa)108.4Shear modulus (GPa)43.4Bulk modulus (GPa)72.0Vapour pressure Temperature (K)40060080010001200140016001800200022002400Pressure (Pa)1.47
x 10-60.653---------

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Podcasts

Podcasts

Listen to Zinc Podcast

Transcript :

Chemistry in its element: zinc

(Promo)

You're listening to Chemistry in its element brought to you by Chemistry World, the magazine of the Royal Society of Chemistry.

(End promo)

Chris Smith

This week the chemical behind calamine lotion for itchy skin, anti dandruff shampoo for a flaky scalp and underarm deodorant for - well, I think we've probably all stood next to someone whom we wish knew a bit more about the chemistry of zinc. Here's Brian Clegg.

Brian Clegg

There aren't many elements with names that are onomatopoeic. Say 'oxygen' or 'iodine' and there is no clue in the sound of the word to the nature of the element. But zinc is different. Zinc - zinc - zinc - you can almost hear a set of coins falling into an old fashioned bath. It just has to be a hard metal.

In use, Zinc is often hidden away, almost secretive. It stops iron rusting, soothes sunburn, keeps dandruff at bay, combines with copper to make a very familiar gold-coloured alloy and keeps us alive, but we hardly notice it. This blue-grey metal, known commercially as spelter, is anything but flashy and attention-grabbing. Even the origins of that evocative name are uncertain.

The dictionary tells us that the word zinc comes from the German (with a K at the end instead of a C), but how that name came into being is unknown. The earliest reference to zinc was in 1651. The substance was known before - objects with zinc in them date back over 2,500 years, and the Romans used that gold coloured alloy - but zinc wasn't identified as a distinct material in the west until the seventeenth century.

Represented in the periodic table as Zn, zinc is a transition metal, grouped with cadmium and mercury. With the middling atomic number 30, it has five stable isotopes of atomic weight from the dominant zinc 64 to zinc 70, plus an extra 25 radioisotopes.

Because of its hazy origins, it's difficult to pin down one person as the discoverer of the element. Although it seems to have been refined in India as early as the twelfth century, the earliest specific claim to have produced the metal was back in 1668, and a process for extracting zinc from its oxide was patented in the UK in 1738 by metal trader William Champion. But it is usually the German chemist Andreas Marggraf who wins the laurels as 'discoverer' for his 1746 experiment isolating zinc.

Although zinc's history is more than a little hazy, there's no doubting its usefulness. You've only got to look at a galvanized metal roof or bucket to see zinc at work. Galvanization is named after Luigi Galvani, the man who made frog legs twitch with electric current, but galvanization has nothing to do with electrical showmanship. In fact electricity's role is surprisingly subtle.

The most common form of galvanization is hot dip galvanization, where iron or steel is slid through a bath of liquid zinc at around 460 degrees Celsius, forty degrees above its melting point. The coating prevents the object treated from rusting. Initially the zinc simply stops the air getting to the iron, but later the zinc corrodes in preference to iron in an electro-chemical process, acting as a so-called sacrificial anode. This is where the 'galvanic' part of the name comes in. Some galvanization is more literally electrical - car bodies, for example, are electroplated with zinc to apply a thin, even layer.

Zinc's electrical capabilities also extend to the most popular batteries. A traditional dry cell has an outer zinc casing acting as the anode (confusingly the anode, usually thought of as positive, is the negative end of a battery), while a carbon rod provides the cathode, the positive electrode. In the longer lasting alkaline batteries, the anode is formed from powdered zinc (giving more surface area for reaction), while the cathode is made up of the compound manganese dioxide.

But the most visible example of zinc at work doesn't give any indication of this greyish metal - instead it's in an alloy that mixes the sheen of gold with the common touch. When molten zinc and copper are mixed together, the result is bold as brass. In fact, it is brass. Everything from door fixings to decorative plaques for horse collars have been made in this flexible alloy. Any orchestra would be much poorer without its brass instruments. It's even likely to turn up in the zips on your clothing.

Well-polished brass has a pleasant glow - but our most intimate contact with zinc, or to be precise zinc oxide - often comes when dealing with the unwanted glow of sunburn. When I was young and there was little in the way of sun block, sunburned skin would be lavishly coated in soothing pink calamine lotion. The primary ingredient of this is zinc oxide, which is white - it's small amounts of iron oxide that give it that colour. Even now, though, when we can avoid the need for calamine, zinc oxide plays its part. Called Chinese white when it's used in paints, zinc oxide is a good absorber of ultraviolet light - so sun block often contains a suspension of tiny zinc oxide particles - as does most mineral-based makeup.

And that's just the start for this versatile oxide. You'll find it used in fire retardants and foods - where it fortifies the likes of breakfast cereals - in glass and ceramics, in glues and rubber. That surprise appearance on the breakfast table reflects another important side to zinc. We need it to stay healthy. It's one of the trace elements, nutrients that our bodies need in small quantities to keep functioning. It's often present in vitamin supplements, though most of us get plenty from meat and eggs. The zinc ends up in various proteins, particularly in enzymes involved in the development of the body, digestion and fertility. A shortage of zinc in the diet can lead to delayed healing, skin irritation and loss of the sense of taste, and encourages many chronic illnesses.

With zinc also appearing in anti-dandruff shampoos in the form of zinc pyrithione and in underarm deodorants as zinc chloride, this is an element that even makes us more attractive to the opposite sex. Zinc is a hidden star. We're rarely aware of it, unlike its flashier neighbours in the period table, but zinc is a workhorse element that helps us all.

Chris Smith

Bristolbased science writer Brian Clegg with the onomatopoeic element, zinc. Next week, what's lurking in your basement.

Katherine Holt

The first reports of problems associated with radon gas in domestic buildings was in the United States in 1984, when an employee at a nuclear power plant began setting off the radiation detector alarms on his way into work. The problem was eventually traced to his home, where the level of radon gas in the basement was found to be abnormally high.

Chris Smith

But where was it coming from and what was the risk to his health. Katherine Holt will be here with all of the answers and the rest of the Radon story on next week's Chemistry in its Element, I do hope you can join us. I'm Chris Smith, thank you for listening, and goodbye.

(Promo)

Chemistry in its element is brought to you by the Royal Society of Chemistry and produced by thenakedscientists.com. There's more information and other episodes of Chemistry in its element on our website at chemistryworld.org/elements.

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