Boron

5

B

10.811(7)

  • Name: Boron
  • Symbol: B
  • Atomic number: 5
  • Atomic weight: 10.811(7)
  • CAS Registry ID: 7440-42-8
  • Group name: (none)
  • Period number: 2
  • Block: p-block
  • Switch:
  • Compare Element

Description

Boron is a semimetal which has an atomic weight of 10.8111. Boron has a melting point of 3760 °F and a boiling point of 7101 °F. In its natural state, boron is hard and brittle and has a shiny black appearance; at high temperatures boron is an excellent conductor of electricity. Uses of boron include: in the natural form of a borate named borax for cleaning solutions and as a natural remedy for insects infestations, in the form of amorphous boron to give the green color in firework displays, and to provide shields against nuclear radiation.

enlarge image


Isolation

Pure boron is not found free in nature and it must be isolated through chemical processes. The main sources of boron are through borax deposits that are found in Turkey, and the Mojave Desert in California.

enlarge image

Boron is available commercially and so it is not isolated through regular laboratory procedures. There are different procedures that can be used to isolate boron for commercial uses on a large scale. Large amounts of impure boron are isolated by reducing boric anhydride with magnesium through a thermite reaction. Pure crystalline boron is isolated through reducing boron trichloride and hydrogen through vapor phase reduction using hydrogen on an electrically heated filament flow system. Other isolation procedures yield small amounts of pure boron by using the thermal decomposition of the chemical BBr3 ; the chemical boron compound is heated with hydrogen over a tantalum wire to temperatures in excess of 1832 °F. Another isolation procedure involves creating boric acid from borax sources to form a boron oxide; the boric acid is obtained from the borax sources and melted to create boric oxide. The oxide is then reacted with three parts of magnesium to yield pure boron and magnesium oxide.


General
Name Boron
Symbol B
Number 5
Chemical series metalloids
Group 13
Period 2
Block p
Appearance black/brown
Standard atomic weight 10.811(7) g·mol−1
Electron configuration 1s2 2s2 2p1
Electrons per shell 2, 3
Atomic properties
Crystal structure rhombohedral
Oxidation states 3 (mildly acidic oxide)
Electronegativity 2.04 (Pauling scale)
Ionization energies 1st: 800.6 kJ·mol−1
(more) 2nd: 2427.1 kJ·mol−1
(more) 3rd: 3659.7 kJ·mol−1
Atomic radius 85 pm
Atomic radius (calc.) 87 pm
Covalent radius 82 pm
Van der Waals radius
Physical properties
Phase solid
Density (near r.t.) 2.34 g·cm−3
Liquid density at m.p. 2.08 g·cm−3
Melting point 2349 K (2076 °C, 3769 °F)
Boiling point 4200 K (3927 °C, 7101 °F)
Critical point
Heat of fusion 50.2 kJ·mol−1
Heat of vaporization 480 kJ·mol−1
Heat capacity (25 °C) 11.087 J·mol−1·K−1
Miscellaneous
Magnetic ordering nonmagnetic
Electrical resistivity (20 °C) 1.5×104Ω·m
Thermal conductivity (300 K) 27.4 W·m−1·K−1
Thermal expansion (25 °C) 5–7 µm·m−1·K−1
Speed of sound (thin rod) (20 °C) 16200 m/s
Young's modulus
Shear modulus
Bulk modulus (β form) 185 GPa
Poisson ratio
Mohs hardness 9.3
Vickers hardness 49000 MPa
Brinell hardness
CAS registry number 7440-42-8

Print this page Bookmark this page

Hide/View all projects Hide all projects Hide/View all projects

All Projects List

  • Accelerate Rusting
  • Acids And Bases
  • Additive Colors
  • Ant Microphotography
  • Apple Mummy
  • Balloon Rocket Car
  • Barney Banana
  • Bending Water
  • Bernoulli’s Principle
  • Blind Spot in Vision
  • Boiling Point of Water
  • Build an Electromagnet
  • Build an Inclinometer
  • Caffeine And Typing
  • Candle Race
  • Candy Molecules
  • Capillarity of Soils
  • Carbon in the Atmosphere
  • Checking vs. Savings
  • Chemical Metamorphosis
  • Clean Cleaners
  • Cleaning Oil Spills
  • Climbing Colors
  • Cloud Cover
  • CO2 & Photosynthesis
  • Collecting DNA
  • Colorful Celery
  • Coloring Matter in Food
  • Colors And Temperature
  • Composition of a Shell
  • Computer Passwords
  • Construct a Lung Model
  • Corrosiveness of Soda
  • Create a Heat Detector
  • Create Lightening
  • Cultivate Slime Molds
  • Cup of Lava
  • Dehydrated Potato
  • Desalinate Sea Water
  • Detergents and Plants
  • Dissolving in Liquids
  • Dissolving Solutes
  • Distillation of Water
  • Double Color Flower
  • Egg in a Bottle
  • Enzyme Activity
  • Eroding Away
  • Erosion Simulator
  • Evaportating Liquids
  • Expanding Soap
  • Exploding Ziploc
  • Extracting Starch
  • Fans And Body Temp
  • Fertilizer & Plants
  • Filtration of Water
  • Floating Ball Experiment
  • Floating Balloon
  • Fog Formation
  • Font and Memory
  • Food and Academics
  • Friction And Vibration
  • Fruit Battery Power
  • Full and Low Fat Foods
  • Galileo's Experiment
  • Gas To Liquid
  • Grape Juice & Cleaners
  • Gravity and Plants
  • Green Slime
  • Growing a Crystal
  • Growing Bread Mold
  • Growing Population
  • Haemoglobin Binding
  • Hard vs. Soft Water
  • Homemade Floam
  • Home-made Geodes
  • Home-Made Glue #1
  • Homemade Snowflakes
  • Home-made Stethoscope
  • Homemade Volcano
  • Homemade Windmill
  • Human Battery Power
  • Inertia of an Egg
  • Information and CD’s
  • Invisible Ink
  • Isolation of Bread Mold
  • Isolation of DNA
  • Jar Compass
  • Lemon Floaties
  • Levers And Force
  • Lift an Ice Cube
  • Light Colors and Plants
  • Long Lasting Bubbles
  • Magic Balloons
  • Magnified Light
  • Make a Compost Pile
  • Make a Fuse Model
  • Make a Parallel Circuit
  • Make An Elevator
  • Make Electric Circuits
  • Make Limestone
  • Make Objects Float
  • Make Static Electricity
  • Make your own sundial
  • Matchbox Guitar
  • Math and Gender
  • Mean, Median and Range
  • Measuring Air Pollution
  • Mentos Soda Volcano
  • Microbial Contaminants
  • Milky Plastic
  • Mini Greenhouse
  • Missing Reflection
  • Mixing With Water
  • Molls Experiment
  • Music and Plants
  • Musical Bottles
  • Nocturnal Plants
  • Ocean Life & Oil Spills
  • Ocean Temperature
  • Optical Mice
  • Oral Bacteria
  • Orange Water Volume
  • Organic vs. Inorganic
  • Osmosis
  • Oven Baked Ice Cream
  • Oxygen & Photosynthesis
  • Paper Bridge
  • Paper Marbling
  • Pascal’s Law
  • Play-Doh and Volume
  • Preserve Spider Webs
  • Pressure Volcano
  • Pulse Rates
  • Pythagorean Tuning
  • Refraction in Water
  • Rollercoasters & Loops
  • Rubber Bones
  • Rubber Heat Reaction
  • Rubbery Egg
  • Rust and Moisture
  • Search Engines
  • Secondary Colors
  • Seed Germination
  • Seed Germination II
  • Separate Salt And Pepper
  • Snappy Sounds
  • Soil Erosion
  • Soil vs. Hydroponics
  • Sound Waves
  • Spectrum through Water
  • Speed of Decomposition
  • Speed of Dissolving
  • Spore Prints
  • Star Observer
  • Static Electricity
  • Statistics and M&M’s
  • Stem-less Flowers
  • Super Strength Egg
  • Sweet Erosion
  • Temperature and CPUs
  • Thirsty Rocks
  • Tornado Demonstration
  • Translucent Egg
  • Transpiration in Plants
  • Typing and Speed
  • Vibrating Coin
  • Volcanic Gas
  • Water and Living Things
  • Water Displacement
  • Water Evaporation
  • Water pH
  • Your Planetary Age