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This figure shows large brown spheres arranged in a cube.
Copper is a metallic solid.

Covalent network solid

Covalent network solids include crystals of diamond, silicon, some other nonmetals, and some covalent compounds such as silicon dioxide (sand) and silicon carbide (carborundum, the abrasive on sandpaper). Many minerals have networks of covalent bonds. The atoms in these solids are held together by a network of covalent bonds, as shown in [link] . To break or to melt a covalent network solid, covalent bonds must be broken. Because covalent bonds are relatively strong, covalent network solids are typically characterized by hardness, strength, and high melting points. For example, diamond is one of the hardest substances known and melts above 3500 °C.

Four pairs of images are shown. In the first pair, a square box containing a black atom bonded to four other black atoms is shown above a structure composed of many black atoms, each bonded to four other black atoms, where one of the upper atoms is labeled “carbon” and the whole structure is labeled “diamond.” In the second pair, a square box containing a white atom bonded to four red atoms is shown above a structure composed of many white atoms, each bonded to four red atoms, where one of the red atoms is labeled “oxygen” and one of the white atoms is labeled “silicon.” The whole structure is labeled “silicon dioxide.” In the third pair, a square box containing a blue atom bonded to four white atoms is shown above a structure composed of many blue atoms, each bonded to four white atoms, where one of the blue atoms is labeled “carbon” and one of the white atoms is labeled “silicon.” The whole structure is labeled “silicon carbide.” In the fourth pair, a square box containing six black atoms bonded into a ring is shown above a structure composed of many rings, arranged into sheets layered one atop the other, where one of the black atoms is labeled “carbon.” The whole structure is labeled “graphite.”
A covalent crystal contains a three-dimensional network of covalent bonds, as illustrated by the structures of diamond, silicon dioxide, silicon carbide, and graphite. Graphite is an exceptional example, composed of planar sheets of covalent crystals that are held together in layers by noncovalent forces. Unlike typical covalent solids, graphite is very soft and electrically conductive.

Molecular solid

Molecular solids , such as ice, sucrose (table sugar), and iodine, as shown in [link] , are composed of neutral molecules. The strengths of the attractive forces between the units present in different crystals vary widely, as indicated by the melting points of the crystals. Small symmetrical molecules (nonpolar molecules), such as H 2 , N 2 , O 2 , and F 2 , have weak attractive forces and form molecular solids with very low melting points (below −200 °C). Substances consisting of larger, nonpolar molecules have larger attractive forces and melt at higher temperatures. Molecular solids composed of molecules with permanent dipole moments (polar molecules) melt at still higher temperatures. Examples include ice (melting point, 0 °C) and table sugar (melting point, 185 °C).

Two images are shown and labeled “carbon dioxide” and “iodine.” The carbon dioxide structure is composed of molecules, each made up of one gray and two red atoms, stacked together into a cube. The image of iodine shows pairs of purple atoms arranged near one another, but not touching.
Carbon dioxide (CO 2 ) consists of small, nonpolar molecules and forms a molecular solid with a melting point of −78 °C. Iodine (I 2 ) consists of larger, nonpolar molecules and forms a molecular solid that melts at 114 °C.

Properties of solids

A crystalline solid, like those listed in [link] , has a precise melting temperature because each atom or molecule of the same type is held in place with the same forces or energy. Thus, the attractions between the units that make up the crystal all have the same strength and all require the same amount of energy to be broken. The gradual softening of an amorphous material differs dramatically from the distinct melting of a crystalline solid. This results from the structural nonequivalence of the molecules in the amorphous solid. Some forces are weaker than others, and when an amorphous material is heated, the weakest intermolecular attractions break first. As the temperature is increased further, the stronger attractions are broken. Thus amorphous materials soften over a range of temperatures.

Types of Crystalline Solids and Their Properties
Type of Solid Type of Particles Type of Attractions Properties Examples
ionic ions ionic bonds hard, brittle, conducts electricity as a liquid but not as a solid, high to very high melting points NaCl, Al 2 O 3
metallic atoms of electropositive elements metallic bonds shiny, malleable, ductile, conducts heat and electricity well, variable hardness and melting temperature Cu, Fe, Ti, Pb, U
covalent network atoms of electronegative elements covalent bonds very hard, not conductive, very high melting points C (diamond), SiO 2 , SiC
molecular molecules (or atoms) IMFs variable hardness, variable brittleness, not conductive, low melting points H 2 O, CO 2 , I 2 , C 12 H 22 O 11

Questions & Answers

wat are hydrocarbon s
Opio Reply
I think they are molecules that comprise only of hydrogen and carbon atoms ( they are organic if I'm not mistaken)
Mmathabo
am new here can I join
Yeko
yes u can
Benita
give two properties of liquid
Grace Reply
molecules are slightly packed and they follow the shape of a container.
Obedie
what is measurement
Isaiah Reply
is the comparison of an unknown quantity with a fixed quantity of the same kind
Sahada
How does an element differ from a compound? How are they similar?
Adeola Reply
an element is an indivisible particles that can take part in a reaction and consist of smaller or tiny particles i.e proton, neutrons and electron while a compound is when two or more element chemically combine together. They are similar when they are homogeneous compound. they take the same rxn.
Yusuf
an element is s chemically pure substance containing a particular type of atoms.. A COMPOUND is a substance containing atoms from different elements..
Inemesit
How to get the Lewis formula of SeCl+3
Erica Reply
hi,I'm new here can I join the conversation
EZEA
what is the structural formula for starch
EZEA Reply
Starch is a mixture (of chemicals) of amylose and amylopectin. Both are macromolecules and polymers. You can search on wikipedia.
Abdelkarim
what is the roles of filter bed
Fathmat
what is the roles of Alu m
Fathmat
what is the roles of chlorine
Fathmat
Roles can be classified or correlate it to different areas: For example: Chlorine can be used in reactions (in industry) to manufacture HCl, which then can be used for other things. Or in swimming pools to kill bacteria. Or as a component in compounds with pharmaceutical roles (drugs). For Al:
Abdelkarim
Its dentisty value is suitable to be used in alloys (mixture of metals) in aircraft bodies. Also, Aluminium foils, Tin cans,.. Some of them are also in Al overhead cables in streets and long roads.
Abdelkarim
what is chemistry
Maxamed
what is the meaning of exceedingly
Yushao Reply
it is an adverb which means extremely
Rohini
what is atomic chemistry?
Gladys Reply
Lewis structure for no3
Gladys
Lewis structure for no3
Gladys
Yes
Gillian
Lewis structure for no3
Nomvelo
what is weak acid
Muhammed Reply
It is an acid which partially ionises in water.
Abdelkarim
what is incandescence
Clifton
what makes it glow
Clifton
why is it red, irange and yellow in color
Clifton
hello am new here and I want to join you
Aliyu
hello
Clifton
hi
Aliyu
too
Gillian
hello i am new here please i want to join this group
Paul
Hi, I'm also new here
Salaudeen
Hi
Keeya
hello guys !!
Sourav
what is pressure?
Slark Reply
The force applied to suction Area of the body
Ahmed
Matter composed of exceedingly small paticle called atom.
Yushao
questions related to metals
Regina Reply
occurrence and preparation of the representatives metals
Regina
list the 20, periodic table and their symbols
Fathmat Reply
hydrogen:h helium;he lithium:l beryllium:be Boron:b Carbon;C Nitrogen:n Oxygen:O FLUORINE:f Neon:n Sodium:s Magnesium:mg Aluminum:a Silicon:s Phosphorus:p Sulphur:s Chlorine:c Argon;a Potassium:p Calcium:c
Benita
Hydrogen, helium, lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine, neon, sodium, magnesium, aluminium, silicon, phosphorus, sulphur, chlorine, argon, potassium, calcium
Cudjoe
Welcome
Gillian
there are 118 known elements ...you numbnuts
what is a solute
Ekezie Reply
Any substance that is disolved in a liqid solvent to create a solution
Fifa
sorry liquid
Fifa
it's a liquid substance
Fathmat
hello group
Ayomide
is the substance that dissolves in the solvent
Amos
so is HCl ionic compound
Honest Reply
No, covalent compound ➡️ molecule. As both H and Cl are non-metals and and form covalent bind by sharing valence e-. But can fully ionice in water forming H+ (a proton, a reason for acidity) and Cl- (anion =Chloride) Hydrogen Chloride is a gas at room; Hydrochloric acid = HCl (aq), dissolved in w
Abdelkarim
Form covalenr bond*
Abdelkarim
The question marks are an emoji in the first sentence is an unread emoji. HCl Covalent compund -> molecule
Abdelkarim
Hi.
Queen
Hi
Calvin
Yh
Cudjoe
yes
Amos
what is chemistry
Chukwu Reply
is the study of composition of substances and the way they behave under different conditions
Amos
how do calculate n1 though n6 any help on understanding the concept
Clifton
is the study of properties of matter and it's component
Grace
Practice Key Terms 8

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Source:  OpenStax, Chemistry. OpenStax CNX. May 20, 2015 Download for free at http://legacy.cnx.org/content/col11760/1.9
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