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C3 Elements and compounds - Coggle Diagram
C3 Elements and compounds
General properties of the transition elements
They are very hard and strong metals and are good conductors of heat and electricity
They have very high melting points and are highly dense metals
Eg the melting point of titanium is 1,688ºC whereas potassium melts at only 63.5ºC, slightly warmer than the average cup of hot chocolate!
The transition metals form coloured compounds and often have more than one oxidation state
Transition metals are often used as catalysts
Metallic bonding
Metal atoms are held together strongly by metallic bonding
Within the metal lattice, the atoms lose their valence electrons and become positively charged
The valence electrons no longer belong to any metal atom and are said to be delocalised
They move freely between the positive metal ions like a sea of electrons
Metallic bonds are strong and are a result of the attraction between the positive metal ions and the negatively charged delocalised electrons
Covalent bonding
Covalent compounds are formed when electrons are shared between atoms
Only non-metal elements participate in covalent bonding
As in ionic bonding, each atom gains a full outer shell of electrons
When two or more atoms are chemically bonded together, we describe them as ‘molecules’
Ionic bonds
An ion is an electrically charged atom or group of atoms formed by the loss or gain of electrons
This loss or gain of electrons takes place to gain a full outer shell of electrons
The electronic structure of an ion will be the same as that of a noble gas – such as helium, neon and argon
Metals: all metals lose electrons to other atoms to become positively charged ions
Non-metals: all non-metals gain electrons from other atoms to become negatively charged ions
The positive and negative charges are held together by the strong electrostatic forces of attraction between opposite charges.
This is what holds ionic compounds together
Ionic compounds
Have high melting and boiling points so ionic compounds are usually solid at room temperature
Not volatile so they don’t evaporate easily
Usually water-soluble as both ionic compounds and water are polar
Conduct electricity in molten state or in solution as they have ions that can move and carry a charge
Covalent compounds
Have low melting and boiling points so covalent compounds are usually liquids or gases at room temperature
Usually volatile which is why many covalent organic compounds have distinct aromas
Usually not water-soluble as covalent compounds tend to be nonpolar but can dissolve in organic solvents
Cannot conduct electricity as all electrons are involved in bonding so there are no free electrons or ions to carry the charge
Link between metallic bonding and the properties of metals
Metals conduct electricity
Electrons entering one end of the metal cause a delocalised electron to displace itself from the other end
Hence electrons can flow so electricity is conducted
There are free electrons available to move and carry charge
Metals are malleable and ductile
Metallic bonding is not disrupted as the valence electrons do not belong to any particular metal atom so the delocalised electrons will move with them
Metallic bonds are thus not broken and as a result metals are strong but flexible
Layers of positive ions can slide over one another and take up different positions
They can be hammered and bent into different shapes without breaking
Metals have high melting and boiling points
There are many strong metallic bonds in giant metallic structures
A lot of heat energy is needed to overcome forces and break these bonds
The formation of ionic compounds, Groups I to VII
Example: Sodium Chloride, NaCl
Method:
Sodium is a group 1 metal so will lose one outer electron to another atom to gain a full outer shell of electrons.
A positive sodium ion with the charge +1 is formed.
Chlorine is a group 7 non-metal so will need to gain an electron to have a full outer shell of electrons.
One electron will be transferred from the outer shell of the sodium atom to the outer shell of the chlorine atom.
A chlorine atom will gain an electron to form a negatively charged chloride ion with a charge of -1.
Formula of ionic compound: NaCl
Ionic Bonds between Metallic & Non-Metallic Elements
Example: Magnesium Oxide, MgO
Explenation
Magnesium is a group 2 metal so will lose two outer electrons to another atom to have a full outer shell of electrons
A positive ion with the charge +2 is formed
Oxygen is a group 6 non-metal so will need to gain two electrons to have a full outer shell of electrons
Two electrons will be transferred from the outer shell of the magnesium atom to the outer shell of the oxygen atom
Oxygen atom will gain two electrons to form a negative ion with charge -2
Formula of ionic compound: MgO
The lattice structure of ionic compounds
Lattice structure
Lattice structure refers to the arrangement of the atoms of a substance in 3D space
In lattice structures, the atoms are arranged in an ordered and repeating fashion
The lattices formed by ionic compounds consist of a regular arrangement of alternating positive and negative ions