Matter & Properties
This scientist arranged elements by atomic mass and left empty spaces for undiscovered ones.
Dmitri Mendeleev
The mass of an ion is essentially the same as this, since charge does not affect it.
neutral atom’s mass
One mole contains this many particles.
6.022 × 10²³, Avogadro’s number
These diagrams represent valence electrons and how atoms bond.
Lewis dot structures
The most reactive metals are found in this group.
Group 1, the Alkali Metals
A property that does not depend on the amount of substance present, such as density, is called this.
intensive property
The smallest particle of an element that retains its properties.
atom
The mass of one mole of a substance in grams is numerically equal to this.
atomic or molecular mass in amu
The central atom is usually this type of atom.
least electronegative atom (not hydrogen)
These elements are nonreactive and do not form ions.
Noble Gases (Group 18)
The principle that compounds always contain the same proportion of their component elements.
Law of Definite Proportions
A pure substance made up of two or more different atom types chemically bonded together.
compound
How many moles are in 36.0 g of water?
2.00 moles
The number of electrons hydrogen needs to be stable.
2 electrons (the duet rule)
The element with the highest known density.
Osmium
A solid changing directly into a gas without becoming a liquid is known as this process.
sublimation
The total number of protons in an element is called this.
atomic number
The number of oxygen atoms in 18 g of H₂O.
6.022 × 10²³ atoms
The formula for calculating formal charge.
Valence e⁻ – (Lone pair e⁻ + ½ Bonding e⁻)
The family with elements that form -2 ions and have 6 valence electrons.
Oxygen Family (Chalcogens, Group 16)
Energy stored due to position or composition is known as this.
potential energy
The sum of the atomic masses of all atoms in a molecule.
molecular mass (molecular weight)
The mass in grams of a single H₂O molecule.
3 × 10⁻²³ g
Molecules like NO that cannot satisfy the octet rule are called this.
P,S,Xe,N, odd-electron molecules.
What is the periodic trend in atomic size across a period.
atomic size decreases across a period