CHEM MCAT incorrect uworld

What does it mean when an isotope keeps the same mass number but its atomic number increases by 1?

beta minus decay

What determines whether two elements have similar chemical properties?

Elements in the same group (same column) have similar chemical properties because they have the same number of valence electrons.

• Same group → same bonding behavior

Valence electrons and ionization

Second ionization energy is low when the second electron removed is still a valence electron (like in Group 2).
It is high when the second electron removed is a core electron (like in Group 1 after losing its only valence electron).

How do you determine ion size within an isoelectronic series?

In an isoelectronic series (same number of electrons), the ion with more protons has the smallest radius because nuclear charge pulls the same electron cloud closer.

Rule:
👉 “Isoelectronic = same electrons. More protons → smaller ion.”

higher ionization means

more energy to remove valence electron

lower ionization means

less energy to remove valence electron

in electron configuration if you remove electrons what do you change

remove Higher (numbered) first

How does surface area affect reaction rate

Heterogeneous catalysis is surface-driven. More surface = more catalysis = faster reaction.

removing reactant

shifts equilibrium to reactants: shifts left

density of water

1g/ml