atomic structure and the periodic table Flashcards
proton number/atomic number
number of protons in the nucleus of an atom
nucleon number/mass number
total number of protons and neutrons in the nucleus of an atom
periods (rows)
indicate the number of energy levels in an atom of the element
groups (columns)
indicate the number of outer shell electrons
what are isotopes
- atoms of the same element which have the same proton number but a different nucleon number
- similar chemical properties due to same valence
- same protons/neutrons but different neutrons
- different physical properties due to different mass
radioactive isotopes
- isotopes can be radioactive or stable
- if they have extra neutrons they may become unstable
- used for cancer treatment, maintaing thickness of material
noble gases
- unreactive
- full outer shells
alloys
- contains atoms of different sizes
- harder/stronger
- resistant to corrosion more
ions
ions are charged particles obtained by the loss or gain of electrons
metal ions
- cations
- lose electrons and become positvely charged
nonmetal ions
- anions
- gain electrons and become negatively charged
when a group 1 metal forms a compound with a group 7 element
- ionic bond formed
- metal atom donates 1 electron to nonmetal atom
- both become stable and form ions
ion forces
ions are held together by the electrostatic forces of atraction between them
structure of ionic compounds
- giant lattice with crystalline sturcture
- regualr arrangement of alternating positive and negatively charged ions
properties of ionic compounds
- high melting and boiling points
- often solid at room temperature
- soluble in water (ion dissociation)
- do not conduct electricity when in solid from but do in aqueous or molten form
- not volatile
covalent bond
formsbetween nonmetal and nonmetal
properties of covalent bond
- low melting and boiling points
- liquids or gases at room temp
- usually volatile with aromas
- insoluble in water but soluble in organic solvents
- cannot conduct electricity
- low melting and boiling point due to weak intermolecular forces
what are examples of
giant covalent structures/macromolecules
diamond and graphite (allotropes of carbon)
diamond characterisitcs
- each carbon atom bonded to four other carbon atoms
- tetrahedral structure
- strong covalent bonds but weak intermolecular forces of attraction
- used in jewellry and cutting tools due to hard nature and high melting point
diamond properties
- extremley hard and dense
- does not conduct electricity
- very high melting point
graphite characterisitics
- each carbon atom bonded to three other carbon atoms
- form hexagonal shaped layers with weak intermolecular forces between the layers which allow them to slide over each other
- free delocalized electrons between the layers
- used as conductors and electrodes for electrolysis because they conduct electricity
- used in pencil lead and lubricators because it is soft and slippery
graphite properites
- soft and slippery because layers can slide over each other
- high melting point
- conducts electricity due to presence of free electrons
silicon oxide characteristics
- each silicon atom bonded to 4 oxygen atoms while each oxygen atom bonded to 2 silicon atoms
- tetrahedral structure
- strong covalent bonds
- cheap and naturally available as sand
metallic bonding
strong electrostatic force of attraction between positive metal ions and delocalised electrons resulting in a giant metallic structure which consists of a regular arrangement of positive metal ions in a sea of free electrons
properties of metal due to bonding
- high melting and boiling point
- malleable and ductile
- conductors of electricity
