Unit 1

Question 1

1. Atomic size (radius)

Answer 1

• as you move down each group, the size of an atom increases because you are adding more orbits or shells
• as you move across a period from left to right, the size of an atom decreases because the positive charge on the nucleus increases causing a greater pull on the widely spaced valance electrons

Question 2

2. Ionization energy (IE)

Answer 2

• the energy required to remove an electron from an atom
• atoms that give up electrons easily have low IEs
• alkali metals have the lowest IEs of all the groups
• noble gases have the highest IEs
• as you move down a group, electrons in the outer energy levels are further form positive nucleus and therefore easier to remove

Question 3

3. Electronegativity

Answer 3

• an indicator of the relative ability of an atom to attract shared electrons
• the positively charged nucleus of a small atom like Fluorine can get much closer to the electrons of another atom, more so than a large atom like cesium
• directly correlated to atomic size

Question 4

4. Electron affinity

Answer 4

• the energy absorbed or released when an electron is added (anion) to a neutral atom
• if energy is needed to add an electron, the resulting anion will be unstable and will soon lose the electron
• if energy is released (made more stable) when an electron is added, the resulting anion will be stable
• EA tends to decrease down a group and increase as you move across a period from left to right

Question 5

Periodic law

Answer 5

the chemical and physical properties of the elements repeat in a regular pattern when they are arranged according to atomic #

Question 6

Groups/columns

Answer 6

vertical

Question 7

Periods/rows

Answer 7

horizontal

Question 8

What is atom?

Answer 8

• smallest particle of an element that still retains the identity and properties of the element
• about 10^-10 m in diameter
• made up of subatomic particles

Question 9

atomic mass unit (u)

Answer 9

• protons and neutrons each have a mass of 1u

- electrons have too small a mass to be acknowledged

Question 10

X

Answer 10

atomic symbol

Question 11

A

Answer 11

atomic mass (# of protons + # of neutrons)

Question 12

Z

Answer 12

atomic # (# of protons)

Question 13

isotopes

Answer 13

atoms of an element that have the same # of protons but diff # of neutrons; similar chem properties just diff mass

Question 14

radioisotopes

Answer 14

unstable isotopes, their nuclei decay releasing subatomic particles

Question 15

modern atomic theory

Answer 15

1. All matter is made up of tiny particles called atoms. Each atom is made up of smaller subatomic particles (e, p, n).
2. The atoms of 1 element can’t be converted into the atoms of any other element by a chemical reaction.
3. Atoms of 1 element have the same properties, such as average mass and size. These properties are different from the properties of the atom of any other element.
4. Atoms of different elements combine in specific proportions to form compounds.

Question 16

Isotopic abundance

Answer 16

the relative amount in which each isotope is present in an element

Question 17

Average atomic mass

Answer 17

the weighted average of the masses of all the elements isotopes (taken into account abundance)