Bonding Flashcards
How are covalently bonded molecules held together?
Atoms with covalent bonds are held together by the electrostatic attraction between the nuclei and the shared electrons. This takes place within the molecule
What dative bonding or co-ordinate bonding?
one atom provides both the electrons
Why/how does co-ordinate or covalent bond happening?
the atom that accepts the electron pair is an atom that does not have a filled outer main level of electrons -the atom is electron-deficient
the atom that is donating the electrons has a pair of electrons that is not being used in a bond, called a lone pair.
What is the structure of metallic bonds?
The number of delocalised electrons depends on how many electrons have been lost by each metal atom.
The metallic bonding spreads throughout so metals have giant structures.
What factors effect the strength of the metals in terms of bonding?
[The charge of the ion] - the greater the charge on the ion, the greater the number or delocalised electrons and the stronger the electrostatic attraction between the positive ions and the electrons
[Size of the ion] - the smaller the ion, the closer the electrons are to the positive nucleus and the stronger the bond.
The delocalised electrons also explain this. These extend throughout the solid so there are no individual bonds to break.
Why metals remain in the same shape after being distorted?
After a small distortion, each metal ion is still in exactly the same environment as before so the new shape is retained
What are the properties of metals?
Metals have high melting points
Metals are malleable and ductile
Metals are good conductors of electricity and heat
Strong in strength
What is electronegativity?
Electronegativity is the power of an atom to attract the electron density in a covalent bond towards itself
What factors effect electronegativity?
The nuclear charge
The distance between the nucleus and the outer shell electrons
the shielding of the nuclear charge by electrons in inner shells.
N.B.
The smaller the atom, the closer the nucleus is to the shared outer main level electrons and the greater its electronegativity.
The larger the nuclear charge ([or a given shielding effect), the greater the electronegativity.
What is electron density?
When chemists consider the electrons as charge clouds,
What is polarity?
Polarity is about the unequal sharing of the electrons between atoms that are bonded together
What is electronegativity like n the periodic table?
Going up a group in the periodic table, electronegativity increases (the atoms get smaller) and there is less shielding by electrons in inner shells
Going across a period in the Periodic Table, the elcctronegativity increases = nuclear charge increases, the number of inner main levels remain the same and the atoms become smaller
most electronegative atoms are found at the top right hand corner of the Periodic Table: Fluorine, Oxygen and nitrogen
What are the types of Intermolecular Forces?
van der Waals - forces act between all atoms and molecules.
Dipole-dipole forces - act only between certain types or molecules
Hydrogen Bonding - acts only between certain types of molecules
What is an intermolecular force?
A force that keeps Molecules and separate atoms are attracted to each other
What is electron pair repulsion theory?
each pair of electrons around an atom will repel all other electron pairs
the pairs of electrons will therefore lake up positions as far apart as possible to minimise repulsion
