chemical level of organisation Flashcards
how many elements are there in the periodic table?
118 elements
what is an element?
a matter which is made up of 1 type of atom and cannot be broken down further
4 elements that account for 96% of body mass
- nitrogen [3%]
- hydrogen [10%]
- carbon [18]
- oxygen [65%]
what is a molecule
a substance that is made of more than 1 type of atom of the same element by chemical bonds
what is a compound
a substance that is made of more than 1 type of atom of the different element
what are isotopes
atoms of the same element with the same number of protons and electron but different numbers of neutrons
what are radioisotopes
isotopes that emit high-energy radiation
[radioactive isotopes]
why do some isotopes release radiation
due to their unstable nuclei
some ways isotopes can be used
- bone scan
- thyroid therapy
- radio-iodine therapy
how do you identify which elements can take part in a chemical reaction
by looking at the valance electrons
[complete valence eletrons] = does NOT participate
-inert elements
[incomplete valence eletrons] = participates
-alkali metals
-transitition metals
-halogens
what is an atom
- the smallest unit of matter
- participates in a chemical reaction
- electrically neutral (p=e)
what is an ion
- atoms/molecules that have lost or gained electrons
- no longer electrically neutral
3 types of chemical bonds
- ionic bond
- covalent bond
- hydrogen bond
what is an ionic bond
electrostatic force of attraction between oppositely-charged ions
formation of the ionic bond [explain]
- a metal atom loses an electron, which is transferred to
the non-metal atom - due to metal and non-metal atom having oppositely
charged ions, they are attracted to each other. - the association of the metal and non-metal ions forms an ionic compound
how is an ionic bond formed
by the transfer of an electron from a metal atom to a non-metal atom
how is a covalent bond formed
by sharing of electrons between two non-metals
2 types of covalent bond
[non-polar covalent bond] = strongest
- pair of electron equally shared between 2 atoms
eg. diamond
[palor covalent bond] = weakest
- pair of electron unequally shared between 2 atoms
eg. water/hydrogen bond in DNA/haemoglobin
what is a hydrogen bond
- a bond that can be easily formed or broken
- important for flexibility and shape of the compound
FUN FACT
the polarity of H2O makes it a universal solvent and change its state