Topic 3: periodicity Flashcards
correct one
what are group 1 elements called?
alkali metals
what are group 2 elements called?
alkali earth metals
what are group 18 elements called?
noble gases
what are group 17 elements called?
halogens
what is the trend in atomic radius?
- Period: decreases
- Group: increases
why does atomic radius decrease across a period?
- no. of protons increases
- no. of electron shells stay the same
- stronger attraction between nucleus and valence electrons
why does atomic radius increases down a group?
no. of occupied electron shells increases
what is the trend in ionic radius?
- cations: decreases
- anions: increases
why does ionic radius increase for anions?
added electrons cause more repulsion between valence electrons
why does ionic radius decrease for cations?
no. of occupied electron shells decreases
Why does first ionisation energy decrease down a group?
the removed electron is from an electron shell further away from the nucleus.
what are the trends in first ionisation energy?
- period: increases
- group: decreases
what is the definition of first ionisation energy?
the energy required to remove one mole of electrons from one mole of gaseous atoms.
what is electron affinity?
the energy released when an electron is added to a gaseous atom.
write the equation to the first electron affinity
X (g) + e⁻ → X⁻ (g)
what are the trends in electron affinity?
- Period: increases
- group: decreases
the second electron affinity is _______________(exothermic/endothermic)
endothermic
why is the second electron affinity an endothermic process?
you’re adding a negatively charged electron to an already negative ion. Since like charges repel, overcoming this repulsion requires energy.
what is electronegativity?
the attraction an atom has for the shared pair of electrons in a covalent bond.
what are the trends in electronegativity?
- Period: increases
- group: decreases
why does electronegativity increase across a period?
- smaller atomic radius
- bonding electrons are held more tightly to nucleus
why does electronegativity decrease down a group?
- larger atomic radius
- bonding electrons are held less tightly to nucleus
What are transition metals?
elements that have incomplete d-orbitals
What is an exception in transition metals?
Zinc
what are the physical properties of transition metals?
- high electrical/thermal conductivity
- high melting points
- malleable + ductile
- high tensile strength
- has magnetic properties
What are the chemical properties of transition metals?
- have more than one oxidation states in compounds
- form complex ions
- form coloured compounds in solution
- can act as catalysts
What is the relationship between the strength of magnetism and the number of unpaired electrons ?
magnetism increases as the number of unpaired electrons increases
What is diamagnetism?
- no unpaired d-electrons
- weakly repelled by an external magnetic field
what is paramagnetism?
- one or more unpaired d-electrons
- attracted by an external magnetic field
- paramagnetism increases with increasing number of unpaired electrons.
What gasses cause acid rain?
- SO3
- SO2
- NO2
what types of oxides form basic solutions when reacted in water?
metallic oxides
what are two metallic oxides?
- Na2O
- MgO
What type of oxide forms amphoteric solutions when reacted with water?
metalloid oxides
What type of oxide forms acidic solutions when reacted with water?
non-metal oxides
What is one metalloid oxide?
Al2O3
