Foundations In Chemistry 2 Flashcards
What is first ionisation energy
The energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ atoms
Factors affecting ionisation energy
Atomic radius, greater the atomic radius, smaller the nuclear attraction
Nuclear charge, greater nuclear charge, greater attraction
Electron shielding, repulsion of outer electrons by inner electrons ( more inner shells= greater shielding effect)
What is an atomic orbital
Electrons inhibit regions of space known as orbitals
What is the heinsenburg uncertainty principle
You cannot know with certainty both where an electron is and where its going next
It is impossible to define with absolute precision, at the same time, both the position and the momentum of an electron
What orbitals are available at the first energy level
1s orbital
What orbitals are available at the second energy level
2p , 2s
How many electrons are in each orbital
2
What is the aufbau principle
Electrons fill low energy orbitals before they fill higher energy ones
What is a shell
A group of atomic orbitals with the same principle quantum number , n
What is ionic bonding
The electrostatic attraction between positive and negative ions
What is electronegativity?
The ability of an atom to attract the pair of electrons in a covalent bond
What happens when two atoms have the same electronegativity
The pair of electrons in the covalent bond are equally attracted to the nuclei
What happens when one atom is more electronegative than the other ?
the electron pair in the covalent bond are close to the more electronegative atoms nucleus
What is the most electronegative element?
FLUORINE
What 3 factors does electronegativity depend on?
- Size of the positive charge on the nucleus
- Atomic radius
- Shielding of the nucleus by electrons in inner shells
How does electronegativity depend on the size of the positive charge on the nucleus?
moving left to right across the period, the number of protons in the nucleus increases
increased positive charge increases the attraction between the nucleus and the pair of electrons in the covalent bond
How does electronegativity depend on atomic radius?
Smaller the atomic radius, the closer the bonding electrons will be to the nucleus of the atom
As we move from down to up across periods the atomic radius increases
As we move across groups the atomic radius decreases
How does the shielding of the nucleus by electrons in inner shells effect electronegativity?
electrons in inner shells screen electrons in the outer shell from the positive charge of the nucleus
Greater number of electrons= lower in electronegativity
What is a dipole?
When an electron pairs much closer to one atom than the other, the separation of charge is called a dipole .
The separation of charge is then called a polar covalent bond.
What are intermolecular forces
Weak forces that act between molecules
What are the three types of intermolecular forces?
Induced dipole- dipole interactions
Permanent dipole- dipole interactions
Hydrogen bonds
What are induced dipole dipole interactions?
Dipoles that are induced from an instantaneous dipole where their is random movements of electrons, causing there to be a slight negative charge on one side compared to the other
What does the strength of London forces depend on?
Number of electrons
What is a permant dipole?
Where two atoms that are bonded have different electronegativities, a polar bond forms. The more electronegative atom draws more of the negative that he towards itself and away the other atom .
Examples of giant covalent structures
Diamond
Graphene
Graphite
Diamond structure and properties
-atoms arranged in a tetrahedral structure
- bond angle of 109.5
-large melting and boiling points due to the large amount of energy required to break the covalent bonds
-does not conduct electricity, every electron is in a covalent bond
-insoluble, solvents cannot disrupt the large number of strong covalent bonds