Chemistry Term 1 Test Revision Flashcards
What can Rate of Reaction be affected by?
How do these things affect the ROR?
Temperature –> high temp. means faster rate (particles move faster in higher temp.)
Concentration –> the more concentrated the reactants are the faster the rate (less space but the same amount of particles means more collisions)
Surface Area –> reactions with a solid reactant can only occur on the surface of the solid, larger SA means more space for collisions to occur and therefore a faster rate
Presence of a Catalyst (a substance that speeds up a chemical reaction) –> less activation energy needed for reaction means faster rate
What is the Collision Theory?
For products to form/a reaction to occur, they must have (activation) energy, collide frequently and effectively and must collide in the correct orientation.
What is similar about valence shells depending on groups (Periodic Table columns)? And what is the exception?
All elements in a group have the same number of electrons in their valence shells. Except for transition metals.
Do Group 1 (alkali metals) elements increase or decrease reactivity as you move down the group?
Increase because the atoms get larger as you go down/the outer electron gets further away from the nucleus. The less attraction there is/the easier it is to lose an electron –> the more reactive the atom is.
Do Group 7 (The Halogens) elements increase or decrease reactivity as you move down the group?
Reactivity decreases down the group. This is because group 7 elements react by gaining an electron. As you move down the group, the amount of electron shielding increases, meaning that the electron is less attracted to the nucleus.
What is electronegativity?
Electronegativity is the ability of an atom to attract electrons towards itself and “hold them tightly.”
Shielding is _______ as you move from left to right but _________ as you move down a group.
Shielding is constant from left to right but increases as you move down. This is because the nuclear core is further from the valence electrons as you move down.
Atomic Radius _______ as you move left to right but ______ as you move down. Why?
Decreases from left to right but increases as you move down. This is because from left to right each element has one more proton than the last, leading to stronger electromagnetic attraction, and therefore the electron cloud is pulled closer to the nucleus. As you move down, however, each element has more electron shell than the previous element, meaning it is larger.
What is Ionization Energy?
The energy needed to take an electron from an atom.
Ionization Energy _________ as you move left to right but ________ as you move down. Why?
Increases from left to right but decreases as you move down. This is because as you move from left to right the atoms become more stable/have more electrons in their valence shell, meaning it will take more energy to remove an electron. As you go down it will decrease because the valence shell becomes further away from the nucleus. The further away from the nucleus, an electron is, the easier it will be to ionize because there is a decrease in attraction to the nucleus.
Electronegativity ________ as you move from left to right but ________ as you move down.
Increases from left to right but decreases as you move down. This is because as you move left to right the elements have a higher effective nuclear charge that makes it harder for electrons to be taken, also meaning atoms can attract and hold on to more electrons. As you go down, it decreases because the increased number of energy levels puts the outer electrons further from the pull of the nucleus, making it easier for them to be taken and harder to be held on to.
What is Nuclear Charge?
The electric charge of the nucleus of an atom.
Nuclear Charge ______ from left to right and _______ as you move down.
Increases both directions
What is Electron Configuration?
The number of electrons in each shell.
What is electron shielding?
Electron shielding describes the ability of an atom’s inner electrons to shield its positively-charged nucleus from its valence electrons.
