105895
Elements Combine to Form Compounds
- An elements reactivity is related to the number of electrons in it outer energy
level (reactivity is a chemical property, Elements in the same group or family
have similar properties). Elements are most stable, or unreactive, when they
have filled outer energy levels.
- The noble gases are very stable. They have filled outer energy levels. The
noble gases neither gain nor lose electrons. Other elements are not as stable
as the noble gases. These elements gain or lose electrons. They become
more stable when they have the same number of electrons in their outer
energy level as the nearest noble gas does.
- The electrons in the outer level are called Valence Electrons. The tendency
to gain or lose electrons is sometimes called Valence. The term Valence
Number is commonly used to describe the number of electrons an element
can gain or lose to combine with other elements. Elements in the same group
or family have the same number of valence electrons.This results in similar
chemical properties.
- For example, the alkali metals lithium, sodium, and potassium are all soft, shiny
metals that react vigorously with water. Each has one valence electron and is
one atomic number away from a noble gas. Each loses one electron to form an
ion with a 1+ charge. The loss of one electron gives them a filled outer energy
level, just like the nearest noble gas.
- In the periodic table, from left to right across a period, atoms gain one valence
electron (and one proton) with each new element. Within a period, electrons are
always added to the same energy level. An element in the second period has
electrons in two energy levels, and an element in the third period has electrons
in three energy levels. The period number indicates the number of occupied
energy levels.
- In the periodic table, from left to right across a period, atoms gain one valence
electron (and one proton) with each new element. Within a period, electrons are
always added to the same energy level. An element in the second period has
electrons in two energy levels, and an element in the third period has electrons
in three energy levels. The period number indicates the number of occupied
energy levels.
- For example, the alkali metals lithium, sodium, and potassium are all soft, shiny
metals that react vigorously with water. Each has one valence electron and is
one atomic number away from a noble gas. Each loses one electron to form an
ion with a 1+ charge. The loss of one electron gives them a filled outer energy
level, just like the nearest noble gas.
- The electrons in the outer level are called Valence Electrons. The tendency
to gain or lose electrons is sometimes called Valence. The term Valence
Number is commonly used to describe the number of electrons an element
can gain or lose to combine with other elements. Elements in the same group
or family have the same number of valence electrons.This results in similar
chemical properties.
- The noble gases are very stable. They have filled outer energy levels. The
noble gases neither gain nor lose electrons. Other elements are not as stable
as the noble gases. These elements gain or lose electrons. They become
more stable when they have the same number of electrons in their outer
energy level as the nearest noble gas does.
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