Atoms elements and compounds

What is an element? Give examples of elements examples of atom

An element is a substance made up of only one atom

Oxygen and copper are examples of atom

What is a compound? Give examples of a compound

Compound is a substance made up of two or more elements that have reacted with eachother and formed chemical bonds between atoms

Water (H20) carbon dioxide (CO2) sodium chloride (NaCl) are compounds

What is an mixture? Give examples of mixture

A mixture is made up of two or more elements but are not chemically bonded together

Air (consisting of molecules such as oxygen and nitrogen) are mixtures

Describe the structure of an atom

The structure of an atom has a central nucleus containing neutrons and protons it is surrounded by electrons arranged in shells

Give the relative charges of electron neutron and proton

Relative charge

Protons +1

Neutron 0

Electrons -1

Give the relative masses of a electron neutron and proton

Relative mass

Proton 1

Neutron 1

Electron 1/1840 (negligible)

Define atomic/proton number

The number of atomic/proton number is the amount of protons present in the nucleus

Define mass/nucleon number

The number of mass/nucleon number is the amount of protons and neutrons in the nucleus

What does the electronic configuration show?

The electronic configuration shows the arrangement of the electrons in each electron shell in an atom

What is unique about the electronic configuration of the noble gases (grp 8)

The noble gases have full outer shell of electrons

The electronic configuration of noble gases end in 8 or 2 (for helium)

How does the group number of a element correspond to their electronic configuration

The number of electrons in the outermost shell is the same as the group number of the element (grp 1-7)

How does the period a element is in correspond to the electronic configuration

The number of electronic shells occupied is the same as the period number the element is in

Define isotopes

Isotopes are atoms of the same element that has the same number of protons but different number of neutrons

Why do isotopes of the same element have the same chemical properties

Isotopes of the same element will have the same chemical properties because the number of electrons stays the same so the electronic configuration stays unchanged

What is relative atomic mass of an atom?

The relative atomic mass is an average value that takes account of the abundance of the isotopes of the element

What is an ion ?

An ion is an atom or molecule with an electrical charge due to the loss or gain of an electron

How is an ionic bond formed ?

Ionic bonds form between a cation and anion this bond is a strong electrostatic attraction between the oppositely charged ions

Describe the m.p and b.p of ionic compounds

Ionic compounds have high m.p and b.p

Describe the electrical conductivity of ionic compounds in molten or solid form

-in molten: good electrical conductivity

-in solid: poor electrical conductivity/cannot conduct electricity

Explain why ionic bonds have high m.p and b.p

Ionic compounds have a giant lattice structure with many ionic bonds these bonds have very strong electrostatic force of attraction so need lots of energy to overcome them

Explain why ionic compounds have good electrical conductivity in molten state

Because there are delocalized electrons which are free to move and carry the charge

How is covalent bond formed ?

A covalent bond is formed when a pair of electrons is shared between to atoms resulting in both atoms having full outer elctron shell

Explain why simple molecular compounds have low m.p and b.p

Because the inter molecular forces are very weak so little energy is needed to overcome them

Explain why simple molecular compounds have poor electrical conductivity

Because there are no ions to carry the charge

Give examples of giant covalent structures

Graphite

diamond

Silicon (lV) oxide

Describe the structure and properties of diamond

In diamond each carbon atom is covalently

bonded to 4 other carbon atoms and arranged In a tehtrahedral 3D shape

-diamond is very hard due to many string covalent bonds

-cannot conduct electricity because there are no delocalized electrons

-can conduct heat because of strong covalent bonding

Describe the structure and properties of graphite

In Graphite each carbon atom is covalently bonded to 3 other carbons and i consists of layers of hexagonal rings with no covalent bonds between the layers

-graphite is very soft since the layers can slide over eachother

-graphite can conduct electricity because each carbon atom has a delocalized electron

Describe metallic bonding

Metallic bonding is the electrostatic force of attraction between the positive ions in a giant metallic lattice and a “sea” of delocalized electrons

Explain why metals can conduct electricity

Metals have metallic bonding so can conduct electricity because the delocalized electrons in their structures can move around and carry the charge

Explain why Metals are malleable and ductile

Metals have metallic bonding so layers of metal atoms can slide over eachother so metals can be shaped and bent