Bromine (Br)

Bromine is a nonmetallic chemical element with an atomic number of 35 in the periodic table of elements. Its pure elemental form is rarely found in Earth’s crust. Being a member of the halogen elements family of the periodic table with seven valence electrons, bromine is highly reactive and easily makes numerous compounds with the other chemical elements.

Chemical and Physical Properties of Bromine

Property	Value
Symbol	Br
Name	Bromine
Atomic number	35
Atomic weight	79.904 g.mol-1
Group	Halogen
Period	2
Color	A dark reddish-brown color
Physical state	A fuming liquid at room temperature
Electronegativity	2.96
Density	3.119 g.cm-3 at 20°C
Melting point	-7.2°C
Boiling point	58.78°C
Ionic radius	1.96 (-1) Å
Isotopes	2
Most characteristic isotope	Bromine-79 and bromine-81
Electronic shell	[Ar] 3d10 4s2 4p5
The energy of the first ionization	1142.7 kJ.mol-1
Crystal Structure	Orthorhombic
Shells	2,8,18,7
Valence	1,3,5,7
Covalent Radius	1.14 Å
Atomic Radius	1.12 Å
Atomic Volume	25.6 cm³/mol
Name Origin	Greek: brômos (stench)
Discoverer	Antoine J. Balard
Year	1826
Location	France
Pronunciation	BRO-meen
Oxidation States	(±1),5
Uses	Dyes, disinfectants, photographic chemicals
Description	Colorless, odorless, tasteless rare noble gas

The reddish-brown liquid of bromine found in nature is a combination of two stable isotopes: bromine-79 (50.54 percent) and bromine-81 (49.46 percent). With the periodic table symbol Br, atomic number 35, and electron configuration [ Ar ] 3d10 4s2 4p5, bromine reaches its boiling point at 58.78°C, while the melting point is achieved at -7.2°C.

Having an atomic mass of 79.904 g.mol -1, bromine is denser than water, but it’s a water-soluble substance. Due to its weight, this gaseous liquid sinks in water. When the red-brown bromide gas reacts with water molecules, hydrobromic acid is produced. 

This member of the halogen family of elements in the periodic table, also labeled as Br2, has an electronegativity of 2.8 according to Pauling, whereas the atomic radius according to van der Waals is 0.165 nm. Characterized by a pungent odor, this easily evaporating gaseous substance at room temperature shares the chemical properties with chlorine and iodine. When compounded with phosphorus, arsenic, aluminium, and antimony, bromine forms volatile reactions. In all aggregate states, bromine retains a diatomic molecular structure.                     

How Was Bromine Discovered?

The Tyrian purple (the royal purple) dye was popular among the ancient civilizations. The first known chemical industry back in the times produced this ancient purple dye. It was composed of 6,6′-dibromoindigo – a bromine compound. 

In 1825, the German student Carl Löwig attempted to replace chlorine with chlorine gas from a sample of magnesium bromide-rich water from a swamp near his home in Bad Kreuznach. To conduct this experiment, the Heidelberg student used ether and the process of distillation. The result was a new chemical element – bromine.

Upon realizing this achievement, his professor encouraged Löwig to produce more of this new chemical element. But, while he was concentrating on this feat, somewhere in France, another professor of chemistry was dedicating his time to the analysis of salt marsh waters and flora.

Namely, a year later, in 1825, the French chemist Antoine-Jérôme Balard (1802, Montpellier, Fr. – 1876, Paris) was interested in what would result if he’d distill the chlorine saturated sodium chloride and sodium sulfate crystals from seawater.

Indeed, the liquid nonmetallic element bromine was the result of this experiment as well. Consequently, because Carl Löwig didn’t publish his findings, Antoine-Jérôme Balard was recognized as the scientist who discovered the new element and its properties. 

How Did Bromine Get Its Name?

As a result of its sharp and unpleasant smell, bromine was named “βρῶμος”, a Greek word denoting strong stench. 

Where Can You Find Bromine?

Even though bromine rarely occurs in nature in its pure elemental form, traces of both soluble and insoluble bromides can be found in Earth’s crust. Due to its high solubility, especially of the bromine ion (Br−), accumulations of this nonmetallic chemical element can be found in the ocean waters. Bromine can be extracted from the ocean waters by performing chemical displacement (oxidation) with carbon tetrachloride and the addition of sulfuric acid:

The deep ocean brine pools, natural bromide salts deposits, brines, and thermal springs are the main locations where bromine is found for commercial exploitation. In addition, the mineral bromyrite is also a source of bromine and its compounds. 

Currently, the United States, China, Mexico, Chile, Jordan, Japan, India, Ukraine, and Israel (the Dead Sea) are the world’s leading bromine production countries. 

Bromine in Everyday Life

The two stable isotopes of bromine, bromine-79 and bromine-81, have a wide application in the medical realm, particularly in radiotherapy. Due to their sedative properties, bromides of sodium, potassium, calcium, ammonium, strontium, and lithium were widely used at the beginning of the 20th  century for the treatment of psychiatric patients. 

Having light-sensitive properties, silver bromide (AgBr) is used for making photographic films, while the fire-protective materials are coated with bromine. The use as a fire retardant is also bromine’s widest application in everyday life. 

Other commercial uses of bromine include water treatment, water purification, dyes, emulsion in citrus-flavored fruit drinks, as an alternative for chlorine used in swimming pools, etc. 

How Dangerous Is Bromine?

Despite the fact that bromine is one of the trace elements in the human body, this chemical substance is highly toxic if inhaled. Characterized by a pungent odor, bromine is easy to detect, so any health hazards can be easily avoided. Although, man-made bromine compounds present an especially hazardous threat to human life and the environment.   

Bromism is a syndrome that occurs as a result of bromine poisoning upon exposure to high levels of this chemical substance. This medical condition was a common occurrence due to the administration of potassium bromide, sodium bromide, and lithium bromide to psychiatric patients. These bromine-based sedatives are nowadays restricted and prohibited in many countries.  

Bromism symptoms experienced by affected individuals include lung problems (if bromine gas is inhaled), skin irritation, coughing, burns, psychosis, fatigue, nausea, hallucinations, unresponsiveness to anything but pain, thyroid gland damage, or dysfunctionality of the nervous system. The most severe cases of bromism may have fatal effects. (Centers for Disease Control and Prevention (CDC), National Institute for Occupational Safety and Health (NIOSH), Pocket Guide to Chemical Hazards).

Environmental Effects of Bromine

In nature, bromine occurs in many inorganic substances. As this chemical substance is often used in various industries, insecticides, and fire-extinguishers, bromide ions (Br−) can additionally accumulate and contaminate water, air, and food. By releasing free bromine atoms in Earth’s atmosphere, bromine has an especially negative effect on the ozone layer.  

Isotopes of Bromine

Bromine has 17 radioisotopes and two stable isotopes: bromine-79 and bromine-81.

Nuclide [n 1]	Z	N	Isotopic mass (Da) [n 2][n 3]	Half-life	Decay mode [n 4]	Daughter isotope [n 5][n 6]	Spin and parity [n 7][n 8]	Natural abundance (mole fraction)
	Excitation energy							Normal proportion	Range of variation
68Br[2]	35	33	67.95836(28)#	~50 ns	p	67Se	3+#
69Br	35	34	68.95011(11)#	<24 ns	p	68Se	1/2−#
70Br	35	35	69.94479(33)#	79.1(8) ms	β+	70Se	0+#
70mBr	2292.2(8) keV			2.2(2) s	β+	70Se	(9+)
					IT	70Br
71Br	35	36	70.93874(61)	21.4(6) s	β+	71Se	(5/2)−
72Br	35	37	71.93664(6)	78.6(24) s	β+	72Se	1+
72mBr	100.92(3) keV			10.6(3) s	IT (>99.9%)	72Br	1−
					β+ (<0.1%)	72Se
73Br	35	38	72.93169(5)	3.4(2) min	β+	73Se	1/2−
74Br	35	39	73.929891(16)	25.4(3) min	β+	74Se	(0−)
74mBr	13.58(21) keV			46(2) min	β+	74Se	4(+#)
75Br	35	40	74.925776(15)	96.7(13) min	β+	75Se	3/2−
76Br	35	41	75.924541(10)	16.2(2) h	β+	76Se	1−
76mBr	102.58(3) keV			1.31(2) s	IT (99.4%)	76Br	(4)+
					β+ (0.6%)	76Se
77Br	35	42	76.921379(3)	57.036(6) h	β+	77Se	3/2−
77mBr	105.86(8) keV			4.28(10) min	IT	77Br	9/2+
78Br	35	43	77.921146(4)	6.46(4) min	β+ (99.99%)	78Se	1+
					β− (0.01%)	78Kr
78mBr	180.82(13) keV			119.2(10) µs			(4+)
79Br	35	44	78.9183371(22)	Stable			3/2−	0.5069(7)
79mBr	207.61(9) keV			4.86(4) s	IT	79Br	(9/2+)
80Br	35	45	79.9185293(22)	17.68(2) min	β− (91.7%)	80Kr	1+
					β+ (8.3%)	80Se
80mBr	85.843(4) keV			4.4205(8) h	IT	80Br	5−
81Br	35	46	80.9162906(21)	Stable			3/2−	0.4931(7)
81mBr	536.20(9) keV			34.6(28) µs			9/2+
82Br	35	47	81.9168041(21)	35.282(7) h	β−	82Kr	5−
82mBr	45.9492(10) keV			6.13(5) min	IT	82Br	2−
					β−	82Kr
83Br	35	48	82.915180(5)	2.40(2) h	β−	83Kr	3/2−
83mBr	3068.8(6) keV			700(100) ns			(19/2−)
84Br	35	49	83.916479(16)	31.80(8) min	β−	84Kr	2−
84m1Br	320(10) keV			6.0(2) min	β−	84Kr	6−
84m2Br	408.2(4) keV			<140 ns			1+
85Br	35	50	84.915608(21)	2.90(6) min	β−	85Kr	3/2−
86Br	35	51	85.918798(12)	55.1(4) s	β−	86Kr	(2−)
87Br	35	52	86.920711(19)	55.65(13) s	β− (97.48%)	87Kr	3/2−
					β−, n (2.52%)	86Kr
88Br	35	53	87.92407(4)	16.29(6) s	β− (93.42%)	88Kr	(2−)
					β−, n (6.48%)	87Kr
88mBr	272.7(3) keV			5.4(7) µs
89Br	35	54	88.92639(6)	4.40(3) s	β− (86.2%)	89Kr	(3/2−,5/2−)
					β−, n (13.8%)	88Kr
90Br	35	55	89.93063(8)	1.91(1) s	β− (74.8%)	90Kr
					β−, n (25.2%)	89Kr
91Br	35	56	90.93397(8)	541(5) ms	β− (80%)	91Kr	3/2−#
					β−, n (20%)	90Kr
92Br	35	57	91.93926(5)	0.343(15) s	β− (66.9%)	92Kr	(2−)
					β−, n (33.1%)	91Kr
93Br	35	58	92.94305(32)#	102(10) ms	β− (89%)	93Kr	3/2−#
					β−, n (11%)	92Kr
94Br	35	59	93.94868(43)#	70(20) ms	β− (70%)	94Kr
					β−, n (30%)	93Kr
95Br	35	60	94.95287(54)#	50# ms [>300 ns]			3/2−#
96Br	35	61	95.95853(75)#	20# ms [>300 ns]
97Br	35	62	96.96280(86)#	10# ms [>300 ns]			3/2−#

Source: Wikipedia

List of Bromine Compounds

As a highly reactive septivalent chemical substance, bromine forms organo-bromides by bonding to carbon. The most prevalent form of this carbon-bromine compound is bromomethane, also labeled as methyl bromide (CH3Br).

Methyl Bromide (CH3Br)

This colorless and odorless gas is considered an ozone-depleting gas when used as a fumigant. Due to this hazardous effect, it was removed from the list of allowed pesticides. In nature, bromomethane is produced by marine life and plants that belong to the cabbage and mustard family of Brassicaceae. 

The list of bromine compounds comprises the following compounds with common oxidation numbers of 5, 3, 1, and -1:

• Dibromoanthracene;
• Astatine bromide;
• Brominated flame retardant;
• Bromine azide;
• Bromine dioxide;
• Bromine monochloride;
• Bromine monofluoride;
• Bromine oxide;
• Bromine pentafluoride;
• Bromine trifluoride;
• Bromo-fluoro-carbon;
• Bromo-xylene;
• Chromium(II) bromide;
• Chromium(III) bromide;
• Cyclopentadienyl magnesium bromide;
• Dibromine monoxide;
• Dibromine pentoxide;
• Dibromine trioxide;
• Dibromo-acetylene;
• Dibromoanthracene;
• Template:Inorganic bromides;
• Phosphoryl bromide;
• Pyridinium perbromide;
• Scandium bromide;
• Tetrabromonickelate;
• Titanium(III) bromide.

The oxidation states of bromine are listed below:

•   0 (elemental bromine, Br2);
• +1 (hypobromite, BrO−); 
• +3 (bromite, BrO−2);
• +5 (bromate, BrO−3); 
• +7 (perbromate, BrO−4). 

5 Interesting Facts and Explanations

1. Tennessine (Ts) is an artificially produced chemical element that may also be considered a part of the family of halogens together with bromine (Br), chlorine (Cl), astatine (At), fluorine (F), and iodine (I).
2. This chemical element with the symbol Br is also labeled as Br2 (dibromine) or brom. 
3. Bromryte (or bromargyrite) is a rare natural insoluble silver mineral that is mostly found in Mexico and Chile. 
4. An ozone-depleting gas is a gaseous chemical substance that lowers the ozone quantities in Earth’s atmosphere.
5. There’s a specific way of storing commercial bromine. Namely, it’s stored in lead or Monel metal-coated barrels, or in glass bottles due to the chlorine it contains.