Nitrogen combines with lithium to form Lithium nitride and similarly can combine with fluorine to form Nitrogen trifluoride. Lithium nitride has a high melting point of 8130C and Nitrogen trifluoride has a low melting point of -2070C. Analyze this information and explain why the melting points are different. Justify your answer with valid scientific reasoning.
Answers
Answer:
Selenium is a chemical element with the symbol Se and atomic number 34. It is a nonmetal (more rarely considered a metalloid) with properties that are intermediate between the elements above and below in the periodic table, sulfur and tellurium, and also has similarities to arsenic. It rarely occurs in its elemental state or as pure ore compounds in the Earth's crust. Selenium—from Ancient Greek σελήνη (selḗnē) "Moon" – was discovered in 1817 by Jöns Jacob Berzelius, who noted the similarity of the new element to the previously discovered tellurium (named for the Earth).
Selenium, 34Se
SeBlackRed.jpg
Selenium
Pronunciation
/sɪˈliːniəm/ (sə-LEE-nee-əm)
Appearance
black, red, and gray (not pictured) allotropes
Standard atomic weight Ar, std(Se)
78.971(8)[1]
Selenium in the periodic table
Hydrogen
Helium
Lithium
Beryllium
Boron
Carbon
Nitrogen
Oxygen
Fluorine
Neon
Sodium
Magnesium
Aluminium
Silicon
Phosphorus
Sulfur
Chlorine
Argon
Potassium
Calcium
Scandium
Titanium
Vanadium
Chromium
Manganese
Iron
Cobalt
Nickel
Copper
Zinc
Gallium
Germanium
Arsenic
Selenium
Bromine
Krypton
Rubidium
Strontium
Yttrium
Zirconium
Niobium
Molybdenum
Technetium
Ruthenium
Rhodium
Palladium
Silver
Cadmium
Indium
Tin
Antimony
Tellurium
Iodine
Xenon
Caesium
Barium
Lanthanum
Cerium
Praseodymium
Neodymium
Promethium
Samarium
Europium
Gadolinium
Terbium
Dysprosium
Holmium
Erbium
Thulium
Ytterbium
Lutetium
Hafnium
Tantalum
Tungsten
Rhenium
Osmium
Iridium
Platinum
Gold
Mercury (element)
Thallium
Lead
Bismuth
Polonium
Astatine
Radon
Francium
Radium
Actinium
Thorium
Protactinium
Uranium
Neptunium
Plutonium
Americium
Curium
Berkelium
Californium
Einsteinium
Fermium
Mendelevium
Nobelium
Lawrencium
Rutherfordium
Dubnium
Seaborgium
Bohrium
Hassium
Meitnerium
Darmstadtium
Roentgenium
Copernicium
Nihonium
Flerovium
Moscovium
Livermorium
Tennessine
Oganesson
S
↑
Se
↓
Te
arsenic ← selenium → bromine
Atomic number (Z)
34
Group
group 16 (chalcogens)
Period
period 4
Block
p-block
Element category
Reactive nonmetal, sometimes considered a metalloid
Electron configuration
[Ar] 3d10 4s2 4p4
Electrons per shell
2, 8, 18, 6
Physical properties
Phase at STP
solid
Melting point
494 K (221 °C, 430 °F)
Boiling point
958 K (685 °C, 1265 °F)
Density (near r.t.)
gray: 4.81 g/cm3
alpha: 4.39 g/cm3
vitreous: 4.28 g/cm3
when liquid (at m.p.)
3.99 g/cm3
Critical point
1766 K, 27.2 MPa