Key concepts in chemistry (1+2) Flashcards
What was the first
atomic model?
and in what year was this created?
Dalton’s solid atom model:
all atoms of an element are identical; different elements have different atoms
1803
When was the electron discovered?
and by who?
1897
Thomson
What atomic model followed the
discovery of the electron?
and in what year was this created?
Thomson’s plum pudding model:
atoms are spheres of positive charge with negative electrons dotted around inside
1904
What atomic model followed the
plum pudding model?
and in what year was this created?
Rutherford’s solar system model:
atoms have a positive nucleus surrounded by negative electrons in orbits
1911
What atomic model followed the
solar system model?
and in what year was this created?
Bohr’s electron shell model:
electrons occupy shells or energy levels around the nucleus
1913
When was the proton discovered?
and by who?
1918
Rutherford
When was the neutron discovered?
and by who?
1932
Chadwick
What is the
relative mass of an electron?
1/1836
Define
mass number.
the total number of protons and neutrons in the nucleus of an atom
Define
atomic number.
the number of protons in the nucleus
Define
isotope.
an atom of an element with the same number of protons but different numbers of neutrons
Define
electronic configuration.
the arrangement of electrons in shells in an atom or ion
Define
cation.
a positively charged ion that is formed when an atom or group of atoms loses one or more electrons
Define
anion.
a negatively charged ion that is formed when an atom or group of atoms gains one or more electrons
What is the formula for a
nitrate ion?
NO3-
What is the formula for a
carbonate ion?
CO32-
What is the formula for a
sulfate ion?
SO42-
What is the formula for a
hydroxide ion?
OH-
What is the formula for a
phosophate ion?
PO43-
What is the formula for an
ammonium ion?
NH4+
What are
ionic bonds?
strong electrostatic forces of attraction between oppositely charged ions
What structure do the
ions in an ionic compound form?
and what does this consist of?
a giant lattice structure
this has:
- a regular arrangement of ions
- ionic bonds between oppositely charged ions
What are the usual melting and boiling points of
ionic compounds?
and why?
- high melting points
- high boiling points
this is because there are many strong ionic bonds and large amounts of energy must be transferred to the lattice structure to break these bonds
Are ionic compounds usually soluble in water?
yes
they dissolve to form aqueous solutions
Define
covalent bond.
the electrostatic attraction between a shared pair of electrons and the nuclei of the two bonded atoms
What are some characteristics of
covalent bonds?
(3)
- strong
- form between non-metal atoms
- often produce **molecules **