a nucleus with protons and neutrons surrounded by a cloud of electrons.
What is an atom?
The smallest particle of an element.
What is an electron?
A negatively charged particle.
What is a nucleus?
A small region at the center of an atom that contains protons and neutrons.
What is a proton?
A positively charged particle.
What is energy level?
The specific amount of energy an electron has.
What is a neutron?
A neutral particle.
What is atomic number?
The number of protons in an atom.
What is an isotope?
An atom with the same number of protons but a different number of neutrons.
What is mass number?
The sum of the neutrons and protons in the nucleus of an atom.
How did Mendeleev discover the pattern that led to the periodic table?
He wrote each element's melting point, density, color, atomic mass and the number of chemical bonds it could form on index cards. He noticed the pattern when he arranged the index cards by increasing atomic mass.
What information about elements does the periodic table provide?
the symbol, the atomic number, and the atomic mass, and whether the element is a solid, a liquid, or a gas and if it is a metal, a metaloid, or a nonmetal.
What is atomic mass?
the average mass of all the isotopes of an element.
What is a period?
the rows of the periodic table.
What is a group?
The columns of the periodic table.
What is a chemical symbol?
one or two letter symbol to identify an element.
What is nuclear fusion?
When two atomic nuclei combine to form a larger nucleus.
What are the physical properties of metals?
shininess, malleability, ductility, and conductivity.
How does the reactivity of metals change across the periodic table?
it decreases as you move from left to right.
What is corrosion?
when a metal is destroyed by reacting with air.
What is an alkali metal?
The metals in group 1 of the periodic table.
What is an alkaline earth metal?
a metal in the second group of the periodic table.
What is a transition metal?
The elements in group 3-13 of the periodic table.
What are the properties of nonmetals?
poor conductors of electricity and heat, reactive with other elements, dull and brittle.