understand that chemical reactions are accompanied by enthalpy changes and these changes can be exothermic (\(\Delta H\) is negative) or endothermic (\(\Delta H\) is positive)

(a) define the terms: - bond energy as the energy required to break one mole of a particular covalent bond in the gaseous state - bond length as the internuclear distance of two covalently bonded atoms (b) use bond energy values and the concept of bond length to compare the reactivity of covalent molecules

define activation energy, \( E_A \), as the minimum energy required for a collision to be effective