Essay 1
Chemistry
Atomic Theory
Atoms, the smallest units of an element that exists as stable and independent unit. Atoms are
indivisible by regular chemical means, but it's possible to divide atoms using some specialized
procedures.
After a short introduction to Atoms, we can use its concept to explain the element and
compound. An element is a substance consisting of only atoms that have the same number of
protons. Elements are made up of one kind of atom, for example, carbon is only made from
carbon atoms. Atoms are composed of two regions, these are the Nucleus and the Electron cloud.
The nucleus is the middle part of the atom that has the mass and has two subatomic particles.
Protons are positively charged and Neutrons are neutrally charged subatomic particles. These
live compacted in the positively charged nucleus and contain most of the mass in an Atom. But,
the negatively charged electrons take a lot of space outside the nucleus, even though they are
small in mass. The subatomic particles in an Atom balance each other. For example, if there are
20 protons in an atom, then there will be 20 electrons to balance the charge of the atom.
Also, the Electron cloud is the part outside the nucleus that has most of the space in the atom.
The Electron cloud is the third subatomic particle, and inside it is the Electron, which is the
subatomic particle negatively charged and has no mass.
The atomic number in an atom indicates the number of protons. For example, Hydrogen’s atomic
number is 1, which means that Hydrogen has only one proton. Such as, Carbon’s atomic number
is 6, which means that Carbon has 6 protons. Similarly, the mass number indicates the number of
protons and neutrons in the nucleus. Hydrogen has one proton and must have two neurons, which
means that it has a mass of 3. So, we have the equation: # of neutrons = mass # - atomic #
(Number of neutrons equals mass number minus the atomic number). Likewise, Li has a mass
number of 7 and an atomic number of 3, this means that it has 3 Protons, and Neutrons can be
found: mass number – atomic number (7-3 = 4). Also, electrons are equal to the number of
protons, so e- = p = atomic number.
The Bohr Model of the atom shows how the particles are arranged.