Atomic Basics
The smallest unit of matter.
atom
This Russian scientist created the first periodic table.
Dmitri Mendeleev
This subatomic particle has a negative charge.
electrons
The symbol for oxygen.
O
The most abundant element in the universe.
hydrogen
The atomic number represents this.
number of protons
This element has the atomic number 1.
Hydrogen
Protons and neutrons are found in this part of the atom.
nucleus
The symbol for carbon.
C
The element that makes up diamonds and graphite.
carbon
These two subatomic particles make up the nucleus of an atom.
protons and neutrons
Elements are arranged on the periodic table in order of increasing this.
atomic number
The charge of an proton.
+1
The symbol for potassium.
K
This gas is essential for human respiration.
oxygen
The outermost electrons of an atom are called this.
Valence Electrons
The periodic table is organized into these vertical columns.
groups
Neutrons differ from protons because they lack this.
charge
The symbol for sodium.
Na
The number of naturally occurring noble gases in the first 20 elements.
3--helium, neon, argon
Atoms of the same element that have different numbers of neutrons are called this.
Isotopes
This element, essential for bones and teeth, has the atomic number 20.
calcium
Electrons orbit the nucleus in these.
energy levels or shells
The symbol for iron.
Fe
This element is commonly used in batteries and has the symbol Li.
lithium