Atoms & Particles
The smallest unit of matter that makes up all substances.
What is an atom?
An atom that has gained or lost electrons.
What is an ion?
Who developed the periodic table?
Mendeleev
Group 1 elements — the most reactive metals.
Alkali metals
These are shiny, malleable, and good conductors.
Metals
This particle has a positive charge and is found in the nucleus.
What is a proton?
A positively charged ion.
What is a cation?
The periodic table is arranged by this property.
Atomic number
Group 2 elements — form basic solutions.
Alkaline earth metals
These are dull, brittle, and poor conductors.
Non-Metals
This particle has no charge.
What is a neutron?
A negatively charged ion.
What is an anion?
Elements along the staircase are called what?
Metalloids
Groups 3–12 — often form colored compounds.
Transition metals
Metals tend to ______ electrons to form ions.
Lose
The particle that moves around the nucleus and has a negative charge.
What is an electron?
Two atoms with the same number of protons but different numbers of neutrons.
What is an isotope?
Groups are the _____ of the table.
Columns
Group 17 — the most reactive nonmetals.
Halogens
Nonmetals tend to ______ electrons to form ions.
Gain
The total number of protons and neutrons in an atom.
What is the atomic mass?
How many electrons does Na²⁺ have?
9 electrons
How many groups and periods are on the table?
18 groups, 7 periods
Group 18 — gases that are inert.
Noble gases
The two elements that are liquids at room temperature.
Mercury (Hg) and Bromine (Br)