Concept two Flashcards
What is an atom?
consists of a nucleus made of protons and neutrons orbited by electrons
What is an electron?
an invisible negatively charged particle that orbits the nucleus of an atom
What is the nucleus?
positively charged center of an atom; contains protons and neutrons
What is a valence electron?
the electrons on the outside electron shell
What are electron shells?
they orbit of electrons around the nucleus of an atom
What are protons?
positively charged particle in the nucleus of an atom
What are neutrons?
neutral particle in the nucleus of an atom
What is the atomic mass?
the mass of an element
How do you calculate the atomic mass?
protons+neutrons
What is a period?
the horizontal rows of elements in the periodic table
What is a group?
the verticle colum of elements in the periodic table
What is the atomic number of an atom?
the number of protons and electrons in an atom of an element
what is an atomic mass unit?
how you measure the atomic mass of an element
what are metals?
shiny, malleable, ductile elements that conducts electricity well
What are metalliods?
elements that have both metallic and non- metallic properties
what are non-metals
dull, brittle elements that do not conduct electricity
What are alkaline metals?
group 1 elements in the periodic table, not including hydrogen; the most reactive of the metals
what are alkaline-earth metals?
group 2 elements in the periodic table; their reactivity is not as strong as that of the alkali metals
What are Halogens?
group 17 elements in the periodic table; the most reactive nonmetals
What are noble gases?
group 18 elements in the periodic table; the most stable and unreactive elements
How do you calculate neutrons?
atomic mass (rounded)-protons
Who was John Dalton?
he put forth the first modern theory of atomic structure
Who was J.J Thompson?
he discovered the electron and proposed the “rasin bun model”
Who was Ernest Rutherford?
he discovered the nucleus
Who was Niel Bohr?
he discovered electron shells
Who was James Chadwick?
he discovered that the nucleus had positively charged particles called protons and neutral particles called neutrons
Where did the word “chemistry” come from?
came from old Egpyt or Greece, meaning “pour together”
