Atoms Flashcards
What Are Atoms?
~ Atoms are the basic building blocks of all materials.
Element
~ An element is a substance made up of only one type of atom.
Molecules
~ A molecule is formed when two or more atoms join (bond) together chemically.
Compound
~ When a molecule is made up of two or more different types of elements chemically combined, we call it a compound.
Structure of The Atom
~ The atom is made up of smaller particles called sub-atomic particles.
These are:
~ Protons ~ Neutrons ~ Electrons
Atomic And Mass Number
Atomic Number:
~The atomic number tells you how many protons (which
is the same as the number of electrons) there are in one atom of the element.
Mass Number:
~The mass number tells you how many protons and neutrons
there are in the atom.
The Modern Periodic Table
~ Vertical columns, called groups, in which the elements with similar physical and chemical
properties (behaviours) are grouped together
~ Horizontal rows, called periods, which are in order of increasing proton number.
The Alkali Metals
~ All the alkali metals have one electron in their outer shell. The atoms ‘want’ to get rid of this
loose electron. As a result, the alkali metals are very reactive and behave similarly.
Group 2
~Alkaline Earth Metals
~ Elements in this group include:
• Beryllium (Be)
• Magnesium (Mg)
• Calcium (Ca).
All elements in this group have two electrons in their outer shell.
Group 7
~ Halogens
~ The elements in group 7 have seven electrons in their
atom’s outer shell.
~ Fluorine (F)
~ Chlorine (Cl)
Group 8 ( Group 0)
~ The Noble Gases
~ The elements in group 8 are all gases and have full outer
shells of electrons in their atoms.
• Helium (He)
• Neon (Ne)
• Argon (Ar), which is used in filament lamps (light bulbs).
What Are Ions?
~ When atoms lose or gain electrons they become charged particles and are called ions.
(• Group 1 - alkali metals. These have only one electron in the outer shell, which they lose to form
a positive ion (+1), e.g. Na”’,
> Group 2 - alkaline earth metals. These have two electrons in their outer shell so will lose two
electrons to form a positive ion (+2), e.g. Mgtz.
Group 6 - non-metals. These have six electrons in their outer shell and so will gain two
electrons for a full outer shell to form a negative ion (-2), e.g. 0-2,
Group 7- halogens. These have seven electrons in their outer shell and so will gain one
electron to form a negative ion (-1), e.g. Cl1.)
How Are Chemical Bonds Formed?
~ A compound forms when two different elements chemically combine.
Ionic Bonds
~ lonic bonding produces a compound that is formed from a metal and a non-metal and is
made up of ions. This occurs when one atom loses electrons and another atom gains electrons.
Covalent Bonding
~ Covalent bonding produces a compound formed from
non-metals in which each atom shares electrons with
another atom.