Chemistry

• Define isotope Atoms of the same element with different number of neutrons and different masses.
• Define relative atomic mass (Ar) Weighted mean mass of an atom of the element compared with 1/12th mass of an atom of carbon-12, which has a mass of 12.
• Define relative isotopic mass The mass of an isotope compared with 1/12th mass of an atom of carbon-12, which has a mass of 12.
• What does a mass spectrometer measure? The mass of isotopes
• How does a mass spectrometer work? Atoms are converted into positive ions.Magnetic field is applied.Deflects positive ions.Ions are separated and can be detected.
• What does the amount of deflection in a mass spectometer depend on? size of particle (heavier deflected less)charge (bigger charges deflected more)
• Equation for relative atomic mass." Ar= isotopic mass x relative abundance + isotopic mass x relative abundance / total abundance
• Define chemical bond A force that holds particles together in a material
• Define simple covalent structure 2 or more non-metal atoms bonded together
• Examples of giant covalent structure diamond graphite boron silicon silicon dioxide
• Giant ionic lattice Metal and non-metal bonded
• Giant metallic The metal elements of the periodic table
• Define covalent bond The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms
• What happens during covalent bonding? Each atom donates a valence electron to the bond.
• Define dative bond A covalent bond where only one of the bonded atoms donates both electrons being shared.
• Examples of molecules with dative bonds. Boron trifluoride/ammonia complex
• Electron pair repulsion theory: shape of simple molecule/ion is determined by number of bonding pairs + lone pairs repel eachother so they are as far apart as possible
• Name of shape with 2 bonding pairs Linear
• Name of shape with 3 bonding pairs Trigonal planar
• Name of shape with 4 bonding pairs Tetrahedral
• Name of shape with 6 bonding pairs Octahedral
• Bond angle of shape with 2 bonding pairs 180 degrees
• Bond angle of shape with 3 bonding pairs 120 degrees
• Bond angle of shape with 4 bonding pairs 109.5 degrees
• Bond angle of shape with 6 bonding pairs 90 degrees and 180 degrees
• 3-D drawing of linear molecule "
• 3-D drawing of tetrahedral "
• 3-D drawing of octahedral "
• Shape and angle between 4 bonding pair and 0 lone pairs 109.5 degrees - tetrahedral
• Shape and angle between 3 bonding pair and 1 lone pair 107 degrees - pyramidal
• Shape and angle between 2 bonding pair and 2 lone pairs 104.5 degrees - V shaped
• What is a induced dipole-dipole interaction Temporary, induced dipole-dipole forces that occur between non-polar molecules.
• The strength of induced dipole-dipole interactions increases as  the number of electrons increase the surface contact increases
• Define electronegativity The ability of an atom to attract the bonding pair of electrons in a covalent bond.
• How do polar molecules occur? When atoms with different electronegativities bond, have permanent dipoles and the molecule is 'unsymmetrical'.
• What is a permanent dipole? When in covalent bonds between different atoms, one atom has a stronger attraction for the shared electrons than the other does. (Substantially different electronegativity)
• Define a symmetrical molecule. All the atoms around the central atom are the same and there are no lone pairs on the central atom.
• Why do symmetrical molecules not have a overall dipole? The dipoles cancel out.
• Define an unsymmetrical molecule. When the central atom has two or more different atoms attached and the central atom has one or more lone pairs.
• Is water polar? Yes because: unsymmetrical - dipoles don't cancel outoxygen more elctronegative than hydrogen