Atomic Structure & Periodic Table
Atoms
The smallest part of an element any smaller and it is no longer that element!
There is a different atom for each element.The number of protons determine the element.
3 protons = Lithium20 protons = Calcium
IF an atom has no charge, then the number of protons (positive charges) equals the number of electrons (negative charges).
Protons
Have a positive chargeEquals the atomic numberEquals the number of electrons, if the atom has
no chargeDetermines the type of elementLives in the nucleus with neutrons
Neutrons
Have no charge
Have mass. So you compute neutrons by atomic mass – atomic number (protons)
Live in the nucleus with the protons
Can vary without changing the type of element
Electrons
Have a negative charge
Can give you the identify of the element IF the atom has no charge
Has almost no mass
Can vary without changing the type of element
Atomic Number
Located above the element’s symbol
Always tells the number of protons and sometimes the number of electrons IF the atom is neutral (no charge)
Atomic mass
The number of protons plus neutrons in an atom. Almost all of the mass is located in the nucleus because electrons have such little mass.
Is often indicated by the name of the element followed by the mass. Example Lithium – 7
Can vary without changing the type of element
Periodic Table
Arranged by
Increasing atomic number (protons)
Why isn’t it arranged by increasing atomic mass?
Periods
Rows
Indicate the number of electron clouds each atom of that element has
NOT ALWAYS THE SAME STATE OF MATTER AT ROOM TEMPERATURE
Families or groupsColumns
All have the same number of electrons in their valence (same number of valence electrons)
All react similarly and have similar physical and chemical characteristics
NOT ALWAYS THE SAME STATE OF MATTER AT ROOM TEMPERATURE
Metals
left of the “zig zag”/staircase.
Metals are:shiny, ductile, malleable, thermally and electrically conductive
MOST but not all are solids
Nonmetals
Located to the right of the “zig zag” or staircase
MOST are gasses at room temperature.
Characteristics of nonmetals include: dull, brittle when they’re a solid and not good
conductors of thermal or electrical energy
Metalloids
Located on the zig zag line.
Have characteristics of BOTH metals and nonmetals in each
Reactivity
The elements on the left of the periodic table are more reactive then the ones to their right.
As you move from left to right, reactivity decreases
Hydrogen
Reacts like a metal but has the characteristics of nonmetals.
The most abundant element in the universe
Describe an atom
Using potassium, describe the atom using the following words:
Proton, neutron, electron, electron clouds, nucleus
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