Unit 1 - core questions Flashcards
define atom
the smallest part of an element that can still be recognised as part of that element
define element
a substance made of only one type of atom
define molecule
a substance made of more than one atom chemically bonded together (can be atoms of the same type)
define compound
a substance made of two or more different atoms chemically bonded together
define mixture
a substance made of more than one thing not chemically bonded together
state the three subatomic particles, their masses, and relative charges
protons neutrons electrons, 1 1 almost 0, +1 0 -1
What did rutherfords alpha scattering experiment prove?
atoms have a small dense nucleus with a positive charge
how did Bohr adapt the model of the atom?
he said the electrons orbit the nucleus at specific distances
what did Chadwick’s work give evidence of?
That the nucleus also contained neutrons as well as protons
What is the atomic number of an atom?
the number of protons in an atom
what is the mass number of an atom?
the number of protons + neutrons in an atom
how do you calculate the number of neutrons in an atom?
mass number - atomic number
how were elements arranged in the early attempts of the periodic table?
by atomic weight
how are elements arranged in the periodic table?
by atomic number
what do you know about elements in the same group?
they have similar properties (reactions) as they have the same number of electrons in the outer shell
why did Mendeleev swap the order of some elements?
so they were in the same group as the elements they had similar properties to
why did Mendeleev leave gaps in his periodic table?
for undiscovered elements
what is an ion?
an atom that has lost or gained electrons so now has a charge
how can solids be separated from liquids?
filtration
what is crystallization?
when a solution is heated until crystals start to form, then left to cool until all the water evaporates
what does distillation do?
separates a mixture of liquids with different boiling points
what decides what element an atom is?
the number of protons
why do atoms have no charge?
they have the same number of protons and electrons
what is the approximate radius of an atom?
0.1nm (1x10^-14m)
how big is the radius of the nucleus compared to that of the atom?
1/10000 the size (so 1x10^-14m)
what is an isotope?
an atom with the same number of protons but a different number of neutrons
how do you calculate the relative atomic mass of an isotope?
multiply the isotope mass by the abundance for each isotope, add them together and divide by 100
what type of ions do metals form?
positive ions
what type of ions do non-metals form?
negative ions
define inert:
unreactive
what is a trend?
a pattern in properties
state the trend in the melting points of the alkali metals
gets lower down the group
what is a displacement reaction?
a reaction in which a more reactive element takes the place of a less reactive element in a compound
what are the common properties of transition metals?
-many transition elements have ions with different charges
-form coloured compounds
-are useful as catalysts
name some common transition metals:
-chromium
-manganese
-iron
-cobalt
-nickle
-copper
