Laws and History
This law states that matter is neither created nor destroyed.
Law of Conservation of Mass
Atoms of the same element that have different numbers of neutrons are called this.
Isotopes
This subatomic particle has a +1 charge and is located in the nucleus.
Proton
Electrons in the outermost energy level of an atom are called this.
Valence
Elements in the same vertical column of the periodic table are called this.
Group / Family
One mole of any substance contains this many particles.
6.022 × 10²³ particles
This philosopher first proposed the idea of indivisible particles called “atomos.”
Democritus
Write the isotope notation for Carbon with 7 neutrons (nuclear symbol).
WB
¹⁴₆C
This subatomic particle has no charge and contributes to atomic mass.
Neutron
Write the electron configuration for Oxygen (full).
WB
1s² 2s² 2p⁴
Elements in the same row have the same number of these.
Energy levels / shells
Convert 0.250 mol of Cu to grams (molar mass = 63.55 g/mol).
15.89 g
This law states that elements can combine in different small whole-number ratios to form different compounds.
Law of Multiple Proportions
Chlorine has two isotopes: Cl-35 and Cl-37. Which has more neutrons?
Cl-37
An atom with 16 protons and 18 electrons would be called this type of particle.
Anion
Draw a Bohr model for Lithium, labeling core and valence electrons.
WB
1st shell: 2 e⁻ (core), 2nd shell: 1 e⁻ (valence)
Which element has the larger atomic radius: Na or Cl?
Na
How many moles are in 36.0 g of H₂O?
2.0 mol
This law states that a compound always contains the same elements in the same proportion by mass.
Law of Definite Proportions
Bromine exists as Br-79 (50.7%) and Br-81 (49.3%). Calculate its average atomic mass.
79.99 amu
How many neutrons are in Aluminum-27?
14 neutrons
Write the noble gas shorthand configuration for Bromine.
WB
[Ar] 4s² 3d¹⁰ 4p⁵
Order the following elements from smallest to largest atomic radius: P, Cl, Na, Mg, S.
WB
Cl < P < S < Mg < Na
Convert 3.01 × 10²³ molecules of CO₂ to moles
0.5 mol
Developed the quantum model where electrons exist in probability clouds/orbitals.
Schrödinger
An element has two isotopes: X-50 (30%) and X-52 (70%). Calculate the element's average atomic mass.
51.4 amu
Fill in the number of protons, neutrons, and electrons for Fe³⁺.
26 p⁺, 30 n⁰, 23 e⁻
Identify the number of valence electrons in an element with configuration: [Ne] 3s² 3p⁵.
7 valence e-
Order these elements from highest to lowest ionization energy: Li, O, F, C, Ne.
Ne > F > O > C > Li
How many molecules are in 56 g of N₂?
1.204 × 10²⁴ molecules