Chem catch up Flashcards
What is the relative mass and charge of the subatomic particles?
Proton: mass 1, charge +1
Neutron: mass 1, charge 0
Electron: mass 1/1840, charge -1
What is the atomic number?
Number of protons.
Number of protons=number of electrons
What is the mass number?
Number of protons and neutrons
Whats an isotope?
Isotopes of an element have the same atomic number, but a differing number of neutrons.
What are noble gases?
Elements with filled subshells are therefore stable.
He, Ne, Ar, Kr, Xe and Rn
How do electrons change their energies?
Absorption (jumping)
Emission (dropping)
From energy levels
What are the different energy levels?
n=1, level s, orbital 2, 2 electrons
n=2, level sp, orbital 2+6, 4+10 electrons
n=3, level spd, orbital 2+6+10, 12+18+28 electrons
What is ionic bonding?
Electrostatic attraction between oppositely charged ions, or between two atoms with different electro negativities.
When atoms transfer electrons they become ionically bonded.
How is solid NaCl ionically bonded?
Na+ and Cl- ions held together in a lattice.
Chlorine receives one electron from sodium, so they have a valency of 1.
What are the properties of ionic compounds?
Strong electrostatic bonds give rise to a high melting point.
Molten ionic compounds conduct electricity as ions able to move.
Soluble in polar solvents, insoluble in non polar solvents.
What is electronegativity?
Ability to gain/lose electrons.
What is covalent bonding?
When two atoms share electrons, in order to attain a noble gas structure.
Usually with atoms close together in the periodic table/similar electro negativities.
Covalent compound Ammonia NH3
Nitrogen 2,5 electrons, needs 3 to fill outer sub shell
Shares 1 electron from H, H shares it’s 1 electron with N.
Nature of covalent compounds:
Weak electrostatic forces mean a low melting point.
They don’t conduct electricity in the molten phase.
They dissolve in non polar solvents.
What makes a molecule polar?
If there’s an asymmetric distribution of charge
