Key Concepts Of Chemistry Flashcards
What is atomic structure?
An atom that consists of a central nucleus, which:
- contains protons and neutrons
- is surrounded by electrons in shells
Atomic timeline
- 1803 Dalton: solid atom model- all atoms of the element are identical
- 1897 Thomson: discovers the electron
- 1904 Thomson: plum pudding model- atoms are spheres of positive charge with negative electrons dotted around inside
- 1911 Rutherford: solar system model- atoms have a positive nucleus surrounded by negative electrons in orbits
- 1913 Bohr: electron shell model- electrons occupy shells
- 1918 Rutherford: discovers the proton
- 1932 Chadwick: discovers the neutron
What are isotopes?
The same number of protons and different number of neutrons.
The mass number is the total number of protons and neutrons in the nucleus.
The atomic number is the number of protons in the nucleus.
What is Mendeleev’s table?
-Mendeleev put the elements in order of the relative atomic mass
- He checked the properties of the element and their compounds
- He swapped the places of some element so that elements with similar properties lined up
- He left gaps where he thought there were other elements, and predicated their properties
- When these elements were discovered, Mendeleev’s predictions fitted the properties very well
The periodic table
Horizontal rows- periods
Vertical rows- groups
Metals are on the left-hand side and in the centre
Non-metals are on the right-hand side
What are electronic configurations?
Electron configuration describes the arrangement of electrons in shells in atom or ion.
Electrons occupy electron shells
Depending what group there in they will all have a different number of electrons on the outer shell
What are ions?
An ion is an atom or a group of atoms with a positive or negative charge
A cation is a positively charged ion and is formed when an atom or group of atoms loses one or more electrons
A anion is a negatively charged ion and is formed when an atom or group of atoms gain one or more electrons
Properties of ionic compounds
Ionic bonds are strong electrostatic forces of attraction between opposing charged ions.
The ions in an ionic compound form a lattice structure with regular arrangement and ionic bond between oppositely charged ions.
- high melting and boiling points
- soluble in water
What are covalent bonds?
A covalent bond is formed when a pair of electrons is shared between two atoms
- strong
- form between non-metal atoms
- produce molecules
Three ways you can represent a covalent bond:
- dot and cross with shells
- dot and cross without shells
- structural formula
What are simple molecular substances?
A simple molecule consists of just a few atoms, joined to each other by covalent bonds
-low melting and boiling points
- weak intermolecular forces
- don’t conduct electricity
- soluble in water
What are giant molecular substances?
A giant molecule consists of many atoms. Atoms are joined by strong covalent bonds and arranged in a regular lattice structure.
- high melting and boiling points
Examples of giant molecular substances
Diamond- each atom bonded to four other carbon atoms
Strong covalent bonds
Graphite- each atom bonded to three other carbon atoms
Weak intermolecular forces between layers
Strong covalent bonds
Graphene- each atom bonded to three other carbon atoms
Regular lattice structure
Conducts electricity
Strong covalent bonds
What are metals?
Metals are:
- shiny
- good electrical conductors
- high density
High melting point
Non- metals are:
- dull
- poor electrical conductors
- low density
- low melting point
Metals have a sea of delocalised electrons
Strong forces of attraction
How do you find the Relative formula mass?
To find the relative formula mass add together all relative atomic masses
Concentration of solution
A solution is a mixture of a solute in a solvent:
- the solute is the substance that dissolves
- the solvent is the substance that the solute dissolves in
What is avogadro’s constant?
6.02x10 to the power of 23
