Atoms and Molecules
Define an atom
The smallest particle of an element
Who created the Periodic Table?
Dmitri Mendeleev
What are valence electrons?
Electrons in the outermost shell
A group of atoms bonded together. Example: h20
Explain the difference between an element and a molecule.
Element = made of one type of atom
Molecule = two or more atoms bonded together
Give an example of a natural element and a man-made element
Natural element exists in nature (example: oxygen)
Man-Made element = made in a lab (example: Plutonium)
How can you predict the number of valence electrons of an element by looking the periodic table?
Group number = number of valence electrons (for most groups)
What do we know about noble gasses and how they react?
Noble gasses are stable. They rarely react.
How can you determine the number of protons, neutrons, and electrons in an atom?
Protons = atomic number
Electrons = same as protons
Neutrons = atomic mass (rounded) minus protons
What information does the atomic number tell you?
The number of protons
Explain the octet rule.
Atoms are stable with 8 electrons in their outer shell. Atoms bond to reach 8.
What is a lattice structure?
A repeating pattern of ions
Why do scientists organize elements into groups and periods?
Groups and periods organize elements by similar properties, valence electrons, and electron shells
What information does the atomic mass tell you?
The number of protons and neutrons in the atom's nucleus
How do valence of electrons reactivity?
It depends on how close they are to a full outer shell. The farther from 8, the more reactive.
Define a covalent bond.
Electrons are shared between atoms
Explain what makes an atom stable or unstable.
Stable atom = full outer shell, nonreactive
Unstable atom = outer shell not full, reactive
Why is the Periodic Table organized by properties instead of just a list?
It shows patterns in properties, reactivity, and electrons, making it easier to predict element behavior
Element X has 6 valence electrons. Element Y has 1 valence electron. Predict how they could make a complete bond.
Element Y (1 valence electron) will lose its 1 electron to Element X.
Element X (6 valence electrons) will gain 2 electrons to reach a full octet — but since Y can only give 1 electron, two Y atoms are needed.
Define an ionic bond (different from a covalent bond)
Electrons are transferred, not shared, between atoms