Atoms, elements and compounds Flashcards
what are all substances made up of
Atoms
what is the radius of an atom
about 0.1 nanometres
1 × 10^-10 m
where is the nucleus in the atom
in the middle of the atom
what is in the nucleus
protons and neutrons
what is the radius of the nucleus
1 x 10^-14
what is the charge of the nucleus and why
1) it has a positive charge
2) because of the protons
where is the mass of an atom
almost the whole mass is concentrated in the nucleus
what is the relative mass and relative charge of a proton
1) relative mass: 1
2) relative charge: +1
what is the relative mass and relative charge of a neutron
1) relative mass: 1
2) relative charge: 0
what is the relative mass and relative charge of an electron
1) relative mass: nearly 0
2) relative charge: -1
where are the electrons in an atom
they move around the nucleus in electron shells, they cover a lot of space
what determines the size of the atom
the volume of the electrons orbits
what is the charge of atoms and why
1) they are neutral
2) because they have the same
number of protons and
electrons
how does the charge on electrons compare to the charge on protons in an atom
they are the same size but opposite, so they cancel each other out
how does the charge on electrons compare to the charge on protons in an ion
the number of protons don’t equal the number of electrons, the electrons are either lost or gained
what does the nuclear symbol of an atom tell you
2 points
1) the atomic (proton) number
2) mass number
what does the atomic number of an atom tell you
how many protons there are
what does the mass number of an atom tell you
the total number of protons and neutrons there are
how do you work out how many neutrons are in an atom
subtract the atomic number from the mass number
draw and label the nuclear symbol for hydrogen
google it
draw and label the nuclear symbol for sodium
google it
what is the definition of an element
an element is a substance made up of atoms that all have the same number of protons in their nucleus
what decides what type of atom an atom is
the number of protons in the nucleus
how many elements are there
118
what is the definition of an isotope
different forms of the same element, which have the same number of protons but a different number of neutrons
what is the difference between the atomic number and the mass number of isotopes
they have the same atomic number but different mass number
compare carbon-12 and
carbon-13
2 points
1) they both have the same number of electrons and protons (6)
2) but carbon-13 has 7 neutrons and carbon-12 has 6
define relative atomic mass
relative atomic mass is an average mass taking into account the different masses and abundances of all the isotopes that make up the element
why is relative atomic mass used
many elements can exist as a number of different isotopes so relative atomic mass is used instead of mass number when referring to an element as a whole
what is the symbol of relative atomic mass
A(r)
what is the formula for relative atomic mass
relative atomic mass = (sum of (isotope abundance x isotope mass number)) / sum of abundances of all the isotopes
copper has 2 stable isotopes.
Cu-63 has an abundance of 69.2% and Cu-65 has an abundance of 30.8%. calculate the relative atomic mass of copper (1dp)
63.6
p18
what is a compound
3 points
1) compounds are substances formed from two or more elements
2) the atoms of each are in fixed proportions throughout the compound
3) they are held together by chemical bonds
how are bonds made
2 points
1) they are made by atoms giving away, taking or sharing electrons
2) the nuclei of atoms aren’t affected
how are compounds formed and separated
by chemical reactions
what is ionic bonding
4 points
1) the bonding between a metal and a non-metal
2) metal atoms lose electrons to form positive ions
3) non-metal atoms gain electrons to form negative ions
4) the opposite charges of the ions mean they are strongly attracted to each other
what is covalent bonding
2 points
1) the bonding between two or more non-metals
2) each atom shares one or more electron with another atom
