Chapter 3 Bonding - ionic, covalent, metal Flashcards
Element
substance that cannot be broken down any further
substance containing atoms with the same atomic number or proton number
compound
Made of different atoms and elements that have been bonded together
Mixture
Different substances that haven’t been bonded together
Signs of a chemical reaction
One or more new substances are formed
Energy taken in or given out
Difficult to reverse
REN
Signs of a physical change
If no new substance is formed it is a physical change
Why do atoms bond
They bond in order to gain stability and have full outer shells
What is a bond
A force of attraction present between two or more atoms, elements, or ions in a compound
Ions
An ion is a charged particle that is formed when an atom gains/looses electrons
Positive ions
Cations A POSITIVE CAT
Negative ions
Anions
Ionic bond
Metal and non-metal
Strong electrostatic force of attraction between ions of opposite charge
Metals form which ion
POSITIVE - CATIONS
Non-metals form which ion
NEGATIVE - ANIONS
NH4
Ammonium 1+
CO3
Carbonate 2-
SO4
Sulfate 2-
SO3
Sulfite 2-
OH
Hydroxide -1
NO3
Nitrate -1
What is a covalent bond
An inter-molecular force of attraction that holds the two atoms together and allows them to share a pair of electrons
2 or more non metals
Molecule
Two or more atoms held together by covalent bonds
Diatomic
Molecules that contain two atoms
What is a covalent compound
A compound formed by atoms of different elements sharing electrons
Methanol
CH3OH
Ethene
C2H4
Properties of ionic compounds
Soluble in water
Can conduct electricity when melted or dissolved in water
High melting and boiling points
Properties of covalent compounds
Lowing melting and boiling points
Insoluble in water
Don’t conduct electricity
Allotropes
Two forms of the same element
Structure of metals
Lattice of tightly packed positive ions and a sea of delocalized electrons that move freely
Metallic bonds
Electrostatic attraction between positive metal ions and a sea of delocalised electrons
Physical properties of metals
High melting point
Malleable and Ductile
Good conductors of heat
Good conductors of electricity
Best conductor of electricity:
Silver
Delocalised electrons
Electrons that move freely in the metal lattice and aren’t tied to any one ion
What is a single covalent bond
A single covalent bond is formed when two atoms share a pair of electrons which leads to a full outer shell s
what does the nucleus of a hydrogen atom contain
only protons
Describe the giant covalent structure of diamond
Each carbon bonds to 4 other carbon atoms and forms a tetrahedral structure
What are the properties of diamond
Very hard - each atom held by 4 strong covalent bonds
high melting point
Does not conduct electricity - no free ions or electrons to carry charge
Describe the structure of Silicon (IV) oxide and the chemical formula
SiO2
Each silicon atom bonds with 4 oxygen atom. Each oxygen atom bonds with 2 silicon atoms.
properties of silicon (IV) oxide
Similar to diamond because it has a similar tetrahedral structure
Describe the bonding in graphite
Each carbon atom bonds with 3 other carbon atoms. Forms hexagonal rings that form flat sheets. Weak forces lie between the millions of sheets
Properties of graphite
Soft and slippery - sheets slide over each other easily
Good conductor of electricity - Each carbon atom has 4 valence eletrons, but only 3 are used in bonding. 1 electron from each carbon atom free to move around graphite and conduct electricity
Use of diamond, graphite and silicon (IV) oxide
Diamond - tools for drilling and cutting
Graphite - Lubricant for engines
electrodes (electrolysis)
Silicon (IV) oxide - Sand paper, bricks for lining furnaces
Why is the melting point of an ionic compound > covalent compound
Ionic bonds have strong electrostatic force of attraction between ions whereas covalent bonds are have intermolecular forces of attraction.
Requires more energy to overcome electrostatic forces of attraction
Name a covalent compound with a higher melting point than most ionic compounds
Silicon (IV) oxide
Diamond