CHEMISTRY FULL REVIEW

PROVE MRS MAC WRONG AND TEST OUT OF HONORS CHEM PLEASE

protons have what type of charge

positive (+1)

neutrons have what type of charge

no charge

electrons have what type of charge

negative (-1)

an element is defined by the amount of?

protons

Z represents what in the periodic table

atomic number

a neutral atom is a atom with

the same number of protons and electrons

atoms with the same element with different number of neutrons are called

isotopes

mass number formula is

neutrons + protons

The from A-X is usually used to represent

isotopes

In X-A form A represents the

mass number

In X-A form X represents the

chemical name/symbol

Given the form ³⁵Cl the 35 represents the

mass number

Chlorine has two main isotopes: Cl-35 and Cl-37. The average atomic mass is 35.45 u.
Which isotope is more abundant and why?

Cl-35 is more abundant because the average atomic mass (35.45 u) is closer to 35 than 37, meaning Cl-35 occurs more often in nature.

if a atom has 6 electrons and 5 protons this is called a

ion with a negative charge, specifically an anion.

What’s the difference between isotopes and ions?

Ions: Same element, different electrons → charged.
→ Isotopes affect mass; ions affect charge.

What does the Madelung Rule state?

Orbitals fill in order of increasing (n + l). If two orbitals have the same (n + l), the one with lower n fills first.

What are the values of l for s, p, d, f orbitals?

s = 0, p = 1, d = 2, f = 3

Which fills first: 4s or 3d? Why?

4s fills first.
4s: n = 4, l = 0 → (n + l) = 4
3d: n = 3, l = 2 → (n + l) = 5

Order from 1s to 4p based on Madelung Rule

1s → 2s → 2p → 3s → 3p → 4s → 3d → 4p

Who developed the first modern atomic theory?

John Dalton in the early 19th century.

Dalton’s theory said all matter is made of what?

atoms, which are indivisible particles.

According to Dalton, are atoms of the same element identical?

Yes, in his theory, they are identical in mass and properties.

Can atoms be created or destroyed in chemical reactions according to Dalton?

No, atoms cannot be created or destroyed in chemical reactions; they are simply rearranged.

What part of Dalton’s theory is now known to be incorrect?

Atoms of the same element are not always identical (isotopes exist).

ionization energy is

energy required to remove an electron from one mole of gaseous atoms to produce one mole of gaseous ions

What is ionic radius and how does it change when an atom loses or gains electrons?

measure of the size of an ion's electron cloud after it has lost or gained electrons.

• Cation (loses electrons):
  Fewer electrons → less repulsion → electrons pulled closer → smaller ionic radius
  (e.g., Na → Na⁺)

• Anion (gains electrons):
  More electrons → more repulsion → electron cloud expands → larger ionic radius
  (e.g., Cl → Cl⁻)

What factors make atomic radius larger?

1. More energy levels (shells)
   → Moving down a group adds electron shells
   → Outer electrons are farther from the nucleus

2. Lower effective nuclear charge
   → Moving left across a period, fewer protons → weaker pull on electrons
   → Electrons spread out more

3. More electron shielding
   → Inner electrons block outer electrons from the nucleus
   → Outer electrons held less tightly

why does atomic radius increase as you go down the periodic table

more electron levels (or shells) so farther away from the nucleus to and harder to pull it in

why does atomic radius decrease as you go right the periodic table

atomic number increases so the number of protons pulling the electrons in does aswell.

What is atomic radius, and how is it different from the distance where protons pull electrons to form ions?

• average distance from the nucleus to the outer edge of the electron cloud in a neutral atom.

• It measures the size of the atom before it gains or loses electrons.

• The pull from protons affects the atomic radius, but the radius itself shows where electrons usually are, not just where protons can pull electrons in or out.

• When an atom becomes an ion:

  • Losing electrons (cation) → radius decreases

  • Gaining electrons (anion) → radius increases

how bad a atom wants a electron is

electron affinity
more negative means it wants it badly

positive means it doesnt. (favorable)