Basic
Chemistry
In the class, we reviewed basic concepts of
elements, compounds, and bonds between atoms.
Atomic number = number of protons = number
of electrons
Atomic mass number = number of protons +
number of neutrons
Difference between an element and a
compound: Both are pure substances. An element is made of same type of atoms,
whereas a compound is made of different elements in definite proportions.
Isotopes of an element have different
number of neutrons. Some isotopes are very useful in chemical and biological
research: Carbon dating uses the decay of Carbon-14 to estimate the age of
organic materials and Calcium-47 helps researchers study the cellular functions
and bone formation in mammals.
Ionic Bond: Atoms transfer valence electrons
to form an ionic bond between them.
Covalent Bond: Atoms share valence electrons
to form a covalent bond between them.
These two bond formations can be
illustrated through Lewis Dot Structure.
Strong covalent bonds and weak bonds are
both important because strong covalent bonds link atoms to form a cell's
molecules and weak bonds can be broken down and can be made again easily.
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