atomic structure and periodic table Flashcards
what do atoms have a radius of
about 0.1 nanometer (that’s 1x10^-10 metres
describe the structure of an atom use the terms proton, neutron, electron, nucleus and shell in answer
atoms have a small nucleus surrounded by electrons. The nucleus is in the middle of the atom and contains protons and neutrons. The electrons occupy shells around the nucleus
what is the relative size of the nucleus compared to the atom
the nucleus is about 1/10,000 the size of an atom
whats the relative charge of :
proton
neutron
electron
proton: +1
neutron: 0
electron: -1
what is the relative mass of a proton
1
are atoms uncharged particles?. Explain why
Theyre uncharged particles as they have the same number of protons as electrons and protons and electrons have opposite chargers of the same size, so cancel each other out
how does an atom become an ion
if some electrons are added or removed the atoms become charged and is then an ion
what decides what type of atom it is
its the number or protons in the nucleus that decides what type of atom it is
an atom w one proton in its nucleus is hydrogen
an atom w two protons is helium
whats an ion?
its an atom or group of atoms that has lost or gained electrons
definition of acid
a substance that releases h+ ions in water (pH<7)
give examples of bases
sodium hydroxide - NaOH, potassium hydroxide - KOH, calcium hydroxide - Ca(OH)2, ammonia - NH3
definition of base
a substance that reacts with an acid to form a salt
whats a alkali
a soluble base (pH>7)
whats an indicator
a chemical that changes colour depending on whether it’s an acid or alkali
what does metal oxide + acid go to
e.g. copper oxide + sulfuric acid –> ….
metal oxide + acid —> salt + water
copper oxide + sulfuric acid –> copper sulfate + water
why will reacting a metal oxide with an acid not produce an alkali solution
when reacting a metal oxide with an acid, it will not produce an alkali solution due to the excessive metal oxide not reacting
metal + acid –> ….
magnesium + sulfuric acid –>
metal + acid –> salt + hydrogen (MASH)
magnesium + sulfuric acid –> magnesium sulfate + hydrogen
metal carbonate + acid –>
magnesium carbonate + sulfuric acid–>
metal carbonate + acid –> salt + water + carbon dioxide
magnesium carbonate + sulfuric acid –> magnesium sulfate + water + carbon dioxide
metal hydroxide + acid –>
sodium hydroxide + hydrochloric acid –> …
metal hydroxide + acid –> salt + water
sodium hydroxide + hydrochloric acid –> sodium chloride + water
how was Mendeleev’s periodic table arranged
arranged in order of atomic weight - however some elements were swapped over to fit with the properties of other elements in the group
left gaps
why did Mendeleev leave gaps in periodic table
Mendeleev predicted properties of undiscovered elements and when they were discovered, his predictions were correct
why weresome scientists skeptical about Mendeleevs table
because he mixed metals and non metals and some boxes contained two elements
what ions did metals have
positive ions
what ions do non metals have
negative ions
how is the modern periodic table arranged
ordered in increasing atomic number
why do things in the same group react in a similar way
they have the same number of outer shell electrons
periodicity definition
a repeating pattern of properties at regular intervals
tip - metallic bonding
why do metals have a high melting point
a lot of energy is needed to overcome the strong electrostatic force of attraction between metal ions and delocalised electrons
why r metals a good electrical conductor
delocalised electrons can move and carry charge
why r metals malleable/ductile
positive metal ions are arranged in neat rows that can slide past each other whilst remaining bonded
tip - covalent bonding
why do non metals have low melting points
not a lot of energy is needed to overcome weak intermolecular forces between molecules
tip - covalent bonding
why r non metals electrical insulators
molecules have no overall charge - no charged particles are free to move
why might noble gases be used for filling lightbulbs
they have no need to gain or lose electrons as they have full outer shells of electrons this means they r inert
what do noble gases exist as
monatomic gases .they exist as gases at room temp due to weak forces between atoms
why does boiling point increase down the group (0/noble gas)
increases due to atoms increasing in size (increasing atomic number) so forces r stronger so more energy is needed
alkali solution is due to prescence of what
alkali solution is due to the prescense of hydroxide (*OH-) ions
metal + water –>
metal + water –> metal hydroxide + hydrogen
metal + chlorine –>
e.g. 2Na + Cl2 –>
metal + chlorine –> metal chloride
2NaCl
Metal + oxygen –>
e.g. 4K + O2 –>
metal + oxygen –> metal oxide
4K + O2 –> 2K2O
As group 1 (alkali metals) increase in atomic number (down group) what happens to :
density
strength
melting point
reactivity
density increases
strength increases
melting point decreases
reactivity increases
what does reactivity depend on
depends on how easily the outer electrons is lost to form a 1+ ion
why does reactivity increase down group 1 (alkali metals)
increased atomic radius - outer electron is further from nucleus
increased electron shielding - more full electrons shells between the outer electron and nucleus
decreased nuclear attraction to outer electron so it is more easily lost
what do group 7 (halogens) exist as
diatomic molecules when each atom shares 1 electron in the covalent bond
down group 7 (halogens) why does melting + boiling point increase
as the molecules increase in mass the intermolecular forces increase in strength so more energy is needed to overcome them
what do halogens react w metals to form and what bonding does it have
to form halide ions (F-,BR- ect) by gaining an electron the product has ionic bonding
when halogens react w non metals what molecules does it form e.g. H2 +Cl2 –>
form covalent molecules e.g. H2 + Cl2 -> 2HCl
what does the more reactive halogen displace
more reactive halogen displaces the less reactive of halogen from a compound
order of these most reactive - least reactive
iodine,chlorine.astatine.bromine
most reactive
chlorine
bromine
iodine
least reactive
astatine
what would happen to this equation if displacement happened:
KBr + Cl2 –>
KBr + Cl2 –> 2KCl + Br2
when halogens react what do they gain
when halogens react they gain an electron
why does reactivity decrease down group 7 (halogens)
atomic radius increases - electron gained is further away from nucles
electron shield increases - more full electron shells between nucleus and electron to be gained
weaker force of attraction between nucleus and electron to be gained so therefore gaining of electron is harder
what r properties of transition metals (list 5)
high melting point,high density, high strength, high hardness, low reactivity
why is iron used for construction
hard and strong + low reactivity
definition of catalysts
substance that speeds up rate of a reaction without being used up
