Bonding and Types of Substance (1+2) Flashcards
What are
ions?
charged particles
What are
cations?
positive ions that form when atoms lose electrons
so they have more protons than electrons
What are
anions?
negative ions that form when atoms gain electrons
so they have more electrons than protons
What does an ion name ending in
-ate
mean?
the ion is negative and contains oxygen and at least one other element
ate down
What does an ion name ending in
-ide
mean?
the ion is negative and contains only one element
hydroxide is an exception
Define
ionic bond.
the electrostatic attraction between two or more oppositely charged ions
What is the
structure of ionic compounds?
a giant ionic lattice
- the electrostatic attraction between oppositely charged ions results in positive ions being immediately surrounded by negative ions, and negative ions being immediately surrounded by positive ions
- these ions are held together by strong electrosatic forces
- these forces act in all directions to form a giant lattic structure
What are the positives and negatives of
dot and cross diagrams?
(when representing ionic compounds) (1+, 2-)
+useful for showing how ionic compound are formed and where the electrons in the ions come from
-don’t show the structure of the compound
-don’t show the relative sizes of the ions or how they’re arranged
What are the positives and negatives of
3D models?
(when representing ionic compounds) (2+, 1-)
+show the relative sizes of ions
+show the regular pattern of ions
-only let you see the other layer of the compound
What are the positives and negatives of
ball and stick models?
(when representing ionic compounds) (4+, 1-)
+show the regular pattern of ions
+show how the ions are arranged
+show that the lattice extends beyond what is shown in the diagram
+can show the relative sizes of the ions (if drawn to scale)
-suggest that there are gaps between the ions (which there aren’t)
What are some properties of
ionic compounds?
(melting and boiling points, solubility, electrical conductivity)
- high melting and boiling points
- (mostly) dissolve easily in water
- don’t conduct electricity when solid
- do conduct electricity when molten or aqueous
Explain
melting and boiling points
in relation to ionic compounds.
They have high melting and boiling points due to the strong electrostatic attraction between ions. It takes a large amount of energy to overcome this attraction and break the many strong bonds.
Define
electrical current.
the flow of charged particles
this can either be ions or delocalised electrons
Explain
electrical conductivity
in relation to ionic compounds.
Ionic compounds cannot conduct electricity when solid because the ions are all held in fixed positions and cannot move. When the compound is molten or aqueous, the ions are free to move and they can carry electric charge.
Define
covalent bond.
the electrostatic attraction between a shared pair of electrons and the nuclei of the two bonded atoms
What is a
displayed formula?
a two-dimensional representation of a molecule that shows the covalent bonds as single lines between atoms
What are the positives and negatives of
dot and cross diagrams
when representing covalent bonding? (1+, 2-)
+show which atoms the electrons in a covalent bond come from
-don’t show the relative sizes of the atoms
-don’t show how the atoms are arranged in space