Atomic Structure and Bonding Flashcards
John Dalton
- 1808
- all elements made up of small, indivisible particles (atoms)
- atoms cannot be created or destroyed
- atoms of different elements = different properties
J.J. Thompson
- 1897
- discovered electron
- suggested atom was neutral - equal positive and negative charges
- “plum pudding model”
plum pudding model 
Negative electrons are embedded in a sphere of positive charge
Ernst Rutherford
- 1913
- proved atoms consisted of electrons revolving around a positively charged nucleus
- named positive charges protons
James Chadwick
- 1932
- nucleus has two different types of particles
- neutral particle called neutron
- difficult to detect - no charge
Relative mass of proton
1
Relative charge of proton
+1
Where is the proton located?
Nucleus
Relative mass of neutron
1
Relative charge of neutron
0
Where is the neutron located?
Nucleus
Relative mass of electron
1
—-
1840
Relative charge of electron
-1
Where is the electron located?
Shells
Atomic number
Number of protons in the nucleus of an atom - smaller number
Mass number
Total number of protons and neutrons in the nucleus of an atom - larger number
charge of an atom
- as a whole an atom has no electrical charge
- equal numbers of protons and electrons cancel each other out
Group number
- number of electrons in the outer shell
- horizontal columns
Period number
- number of shells in use
- vertical columns
Radius of an atom
distance between centre of nucleus and furthest electron from nucleus
How big is an atoms radius?
0.1 nanometres (nm)
- 1 x 10-9 m
- 1000000000 nm = 1m
Radius of nucleus is less than 1/10000 th of atom
Isotope
atoms that have the same number of protons (so they are atoms of the same element), but they have a different number of neutrons (so they have a different mass number).
Relative atomic mass (Ar) of chlorine
The mass number of chlorine is given as 35.5 in the periodic table because it is the average mass taking into account the two isotopes
75% 35 Cl and 25% 37 Cl
Ar = (35 x 75) + (37 x 25)
—————————- = 35.5
100
Allotropes
- different forms of the same element in the same state
- e.g Carbon = diamond, graphite and graphene
- chemically similar to isotopes because they have the same number of electrons
Cation
- Positive ion
- metals lose electron to form them
Anion
- Negative ion
- Non-metals gain electrons to form them
Why do ions form?
- All elements what to achieve the stability of a nobel gas
- They can achieve this by having a full outer shell of electrons
What are ions?
Charged particles formed when atoms lose or gain electrons to achieve a full outer shell
What do ions have the same electronic structure as?
A noble gas
What is the number of a charges on an ion equal to?
The valency
Molecular ions
Charged particles containing more than one atom
E.g sulfate ion SO4 -2
Chemical bonding
if an atom doesn’t have a full outer shell of electrons it will react with another atom to achieve a full outer shell
How many types of chemical bonding are there?
Three:
- ionic
- covalent
- metallic
How does an ionic bond form?
- occurs between metals and non-metals
- ionic bonds form when a metal transfers electrons to a non-metal
- forming positive and negative ions
What is an ionic bond?
The electrostatic force of attraction between oppositely charged ions
They are strong and require a substantial amount of energy to break them
What does covalent bonding occur between?
- between non-metals atoms only
- involves sharing pairs of electrons
What is a covalent bond
- co = share
- valency = number of electrons in outer shell
- share one of their outer shell electrons with each other to form a shared pair of electrons
- covalent bonds within molecules are strong and require a substantial amount of energy to break
Single covalent bond
One shared pair of electrons
Covalent bond
Show outer shell only
Bonding electrons
Pairs of electrons that are part of a covalent bond
Lone pair of electrons
Pairs of electrons that are not involved in a bond
Triple covalent bond
Three shared pairs of electrons
Double covalent bond
Two shared pairs of electrons
Diatomic molecules
Two atoms covalently bonded e.g H2
Simple/molecular covalent structure
- Small molecules
- Simple covalent molecules
- weak intermolecular forces of attraction between molecules called van der Waals forces
What are van der Waals’ forces?
Weak intermolecular forces of attraction between molecules
What is the electronic conductivity of molecular/simple covalent compounds?
Poor
- no free ions or electrons to move and carry charge
What is the electronic conductivity of ionic compounds?
Poor
- when solid ions are held rigidly, not free to move and carry charge
What is the melting/boiling point of ionic compounds
High
- strong forces of attraction between the oppositely charged ions which require a substantial amount of energy to break
What is the solubility in water of ionic compounds?
Soluble
What is the structure of ionic compounds?
Giant ionic
What is the bonding in ionic compounds?
Ionic
What is the melting/boiling point of molecular/simple covalent compounds?
Low
- weak van der Waals’ forces between the molecules which require a small amount of energy to break
What is the solubility in water of molecular/simple compounds?
Insoluble
What is the structure of molecular/ simple covalent compounds?
Simple/molecular covalent
What is the bonding in molecular/ simple covalent compounds?
Covalent
giant covalent structure
Covalently bonded atoms which extend in all directions for millions of atoms
Diamond
giant covalent structure
allotrope of carbon
does not conduct electricity
- no delocalised electrons to move and carry charge
high melting point
- strong covalent bonds between carbon atoms which require a substantial amount of energy to break
Graphite
giant covalent structure
allotrope of carbon
soft substance
- hexagonal rings of carbon atoms arranged in layers, held together by weak forces, delocalised electrons, slip over each other
Conducts electricity
- delocalised electrons, move and carry charge
High melting point
- strong covalent bonds between carbon atoms which require substantial amount of energy to break
Graphene
giant covalent structure
allotrope of carbon
very strong
- strong covalent bonds
- 100x stringer than steel
conducts electricity
- delocalised electrons
very light
- one atom thick
high melting point
- strong covalent bonds which require substantial amount of energy to break
High melting point
strong covalent bonds between carbon atoms which require substantial amount of energy to break
Conducts electricity
delocalised electrons, move and carry charge
Uses of diamond
Cutting tools
Uses of graphite
Pencils and lubricants
Uses of graphene
Solar cells and batteries
What is the electrical conductivity of giant covalent compounds?
diamond
- poor
graphite
- good, delocalised electrons which move and carry charge
- exception
graphene
- good, delocalised electrons which move and carry charge
- exception
What is the melting/boiling point of giant covalent compounds?
High
- strong covalent bonds between the carbon atoms which require a substantial amount of energy to break
What is the solubility in water of giant covalent compounds?
Insoluble
What is the structure of giant covalent compounds?
Giant covalent
What is the bonding of giant covalent compounds?
Covalent
Metallic bond
Strong force of attraction between positive metal ions in a regular lattice and the delocalised electrons
Giant metallic structure
Sea of delocalised electrons acts like an “electronic glue” holding metal ions together
What is the electronic conductivity of metals?
Good
- delocalised electrons move and carry charge
What is the melting/ boiling point of metals?
High
- strong forces of attraction between positive ions and delocalised electrons
- strong metallic bonds which require a substantial amount of energy to break
Solubility in water of metals
Insoluble
Structure of metals
Giant metallic
Bonding of metals
Metallic
How are bonding and structure not the same?
Bonding
- covalent
- ionic
- metallic
Structure
- molecular covalent
- giant ionic
- giant covalent
- giant metallic
Alloy
Mixture of two or more elements, at least one of which has metallic properties
How do you find the % gold in an alloy?
No carats
————— x 100
24
Aluminium uses
Uses
- alloys for aircraft
- over head electrical wiring
Property related to use
- low density/ light weight
- good conductor of electricity
- low density
Iron uses
Use
- bridges
- structures
Property related to use
- strong
- abundant
- cheap
Copper uses
Use
- plumbing
- coinage/ brass
Property related to use
- malleable
- unreactive with water
- unreactive
- strong
Magnesium uses
Use
- flares
- alloys for aircraft
Property related to use
- burns with bright, white light
- Mg combined with other metals makes high strength, low density
Benefits of alloys
- hardness
- electrical conductivity
- resistance to corrosion
Iron: Property related to use
- strong 💪
- abundant 🌱
- cheap ⬇️💰
Copper: Property related to uses
- malleable 🧙♂️
- unreactive with water 💦🚫
- unreactive 🚫
- strong 💪
Aluminium: Property related to use
- low density/ light weight 🪶
- good conductor of electricity ⚡️
- low density 🪶
Magnesium: Property related to use
- burns with bright, white light 🔥💡
- Mg combined with other metals makes high strength, low density 💪 🪶
