Atoms , Bonding And Polarity Flashcards
(20 cards)
What is an isotope
An atom of the same element with the same number of protons and electrons but a different number of neutrons
What is an ion
An atom of an element with the same atomic or mass number but a different number of electrons so it had a positive or negative charge
What is relative atomic mass
The weighted mean mass of an atom of a given element given relative to 1/12 the mass of a carbon 12 atom
What is relative isotopic mass
The mass of a given isotope relative to 1/12 of the mass of a carbon 12 atom
How is atomic mass measured
Using a mass spectrometer which music be calibrated by running carbon finding carbon 12 and setting the mass to 12
Ionisation: gaseous sample bombarded by high energy electrons to knock off an electron and turn it into a positive ion
Acceleration: accelerated by an electrical field
Deflection: deflected using a magnetic field and the angle of deflection depends on the mass
Detection: calibrated to record the deflection and interpret it in terms of mass
What are the shapes of the orbitals
S orbital- spherical
P orbital- figure of 8
D orbital- 2 figures of 8 perpendicular
Definition of orbital
A region sound the nucleus of an atom that can hold two electrons with opposite spins
How do electrons go into the orbitals
An electron will always go into the lowest energy orbital
The electron will occupy an empty orbital of the same energy level in preference to one that already has an electron in it
Ionisation energy
The outermost electrons are removed one at a time from an atom and the energy required is measured
D block anomaly
Will lose electrons from the s sub shell instead of the d sub shell
The d sub shell moves down in energy so the electrons from the s sub shell are lost instead
What are the two anomalies to electron arrangement
Cr and cu
Both have 4s1 so 3d is either half filled or fully filled which is a more stable arrangement
Ionic bonding
The electrostatic attraction between positive metal ions and negative non metal ions
Why do ionic substances have a high melting point
Strong attraction between ions in a lattice
These attractions must be broken which requires a lot of energy so melting point is high
Ions with a higher charge have a stronger attraction so more energy is needed to break these bonds
Describe the solubility of ionically bonded substances in water
They are soluble as water is a polar molecule
The partially negative o is attracted to the positive ion
The partially positive h is attracted to the negative ion
Describe the electrical conductivity of ionically bonded substances
Ionic liquid- ions become free to move so act as mobile charge carriers so substance can conduct
Ionic solid - in an ionic solid the ions are held in a fixed lattice , no mobile charge carriers so cannot conduct
Aqueous solution: in water the ions disassociate and become free to move so there are mobile charge carriers and the substance can conduct
Metallic bonding
The electrostatic attraction between delocalised electrons and positive metal ions
Covenant bond
The electrostatic attraction between the negative shared electrons and a positive nucleus
What is a lone pair
A pair of electrons not involved in the bonding of an atom
Co2 bonding
Linear
180*
BH3 bonding
Trigonal planar
120*
