All metals and non metals are elements or compounds?
Answers
Answer:
elements
Explanation:
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Answer:
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Explanation:
Density: Metals have high density and are very heavy. Iridium and osmium have the highest densities where as lithium has the lowest density.
Melting and Boiling Points: Metals have high melting and boiling point. Tungsten has the highest melting point where as silver has low boiling point. Sodium and potassium have low melting points.
Chemical Properties of Metals
Metals are electropositive elements that generally form basic or amphoteric oxides with oxygen. Other chemical properties include:
Electropositive Character: Metals tend to have low ionization energies, and typically lose electrons (i.e. are oxidized) when they undergo chemical reactions They normally do not accept electrons. For example:
Na0→Na++e−(2.11.1)
Mg0→Mg2++2e−(2.11.2)
Al0→Al3++3e−(2.11.3)
Alkali metals are always 1+ (lose the electron in s subshell)
Alkaline earth metals are always 2+ (lose both electrons in s subshell)
Transition metal ions do not follow an obvious pattern, 2+ is common, and 1+ and 3+ are also observed
Compounds of metals with non-metals tend to be ionic in nature
Most metal oxides are basic oxides and dissolve in water to form metal hydroxides:
Metal oxide + water -> metal hydroxide
Na2O(s) + H2O(l) -> 2NaOH(aq)
CaO(s) + H2O(l) -> Ca(OH)2(aq)
Metal oxides exhibit their basic chemical nature by reacting with acids to form salts and water:
Metal oxide + acid -> salt + water
MgO(s) + HCl(aq) -> MgCl2(aq) + H2O(l)
NiO(s) + H2SO4(aq) -> NiSO4(aq) + H2O(l)
Example
What is the chemical formula for aluminum oxide?
Solution
Al has 3+ charge, the oxide ion is O2-, thus Al2O3
Example
Would you expect it to be solid, liquid or gas at room temp?
Solutions
Oxides of metals are characteristically solid at room temp
Example
Write the balanced chemical equation for the reaction of aluminum oxide with nitric acid:
Solution
Metal oxide + acid -> salt + water
Al2O3(s) + 6HNO3(aq) -> 2Al(NO3)3(aq) + 3H2O(l)
Nonmetals
Elements that tend to gain electrons to form anions during chemical reactions are called non-metals. These are electronegative elements. They are non-lustrous, brittle and poor conductors of heat and electricity (except graphite). Non-metals can be gaseous, liquids or solids.
Physical Properties of nonmetals:
Physical State: Most of the non-metals exist in two of the three states of matter at room temperature: gases (oxygen) and solids (carbon).
Non-Malleable and Ductile: Non-metals are very brittle, and cannot be rolled into wires or pounded into sheets.
Conduction: They are poor conductors of heat and electricity.
Luster: These have no metallic luster and do not reflect light
Conductivity: Poor conductors of heat and electricity
Melting and Boiling Points: The melting points of non-metals are generally lower than metals
Seven non-metals exist under standard conditions as diatomic molecules:
H2(g)
N2(g)
O2(g)
F2(g)
Cl2(g)
Br2(l)
I2(l) (volatile liquid - evaporates readily)
Chemical Properties of Nonmetals
Non-metals have a tendency to gain or share electrons with other atoms. They are electronegative in character.
Nonmetals, when reacting with metals, tend to gain electrons (typically attaining noble gas electron configuration) and become anions:
Nonmetal + Metal -> Salt
3Br2(l)+2Al(s)→2AlBr3(s)(2.11.4)
Compounds composed entirely of nonmetals are molecular substances (not ionic).
They generally form acidic or neutral oxides with oxygen that that dissolve in water react to form acids:
Nonmetal oxide + water -> acid
CO2(g)+H2O(l)→H2CO3(aq)carbonic acid(2.11.5)
(carbonated water is slightly acidic)
Nonmetal oxides can combine with bases to form salts.
Nonmetal oxide + base -> salt
CO2(g)+2NaOH(aq)→Na2CO3(aq)+H2O(l)(2.11.6)
Metalloids
Properties intermediate between the metals and nonmetals. Metalloids are useful in the semiconductor industry.
Metals Non-metals Metalloids
Gold Oxygen Silicon
Silver Carbon Boron
Copper Hydrogen Arsenic
Iron Nitrogen Antimony
Mercury Sulphur Germanium
Zinc Phosphorus
Physical Properties of Metalloids
State: They are all solid at room temperature.
Conduction: Some metalloids, such as silicon and germanium, can act as electrical conductors under the right conditions, thus they are called semi-conductors.
Luster: Silicon for example appears lustrous, but is not malleable or ductile (it is brittle - a characteristic of some nonmetals). It is a much poorer conductor of heat and electricity than the metals.
Solid Solutions: They can form alloys with other metals.
Chemical Properties of Metalloids
Their physical properties tend to be metallic, but their chemical properties tend to be non-metallic.
The oxidation number of an element in this group can range from +3 to -2, depending on the group in which it is located.
Trends in Metallic and Nonmetallic Character