test jan 30 Flashcards
what properties do metalloids lack
The properties of metals they are dull brittle and poor conductors
Who discovered radioactive decay
Henri Becquerel
what are semi conductors
can conduct electricity under some circumstances but not under others
what is an Atom
smallest particle of an element
what atom model did John Dalton create
the round ball model
what atomic model did JJ Thompson discover
blueberry muffin model
which atomic model was bohrs
electron cloud
Who conducted the famous gold foil experiment
Rutherford
James Chadwick discovered what
neutron
this model of the Atom describes the center core-nucleus- containing protons and neutrons surrounded by a cloud like region of moving electrons with varying energy
modern atomic model
what is atomic mass
The average of all the isotopes of an element
Dimitri Mendeleev discovered what
periodic table
what is the atomic number
number of protons in the nucleus of the Atom
Henry Mosley discovered what
that if elements are arranged in order of increasing atomic number than the elements lined up correctly
what are groups or families
vertical columns and periodic table
what are the periods
seven horizontal rows and periodic table
The modern periodic table is organized by what
atomic number
where are metals found on the periodic table
left of the zigzag
what are the majority of elements
metals
what is malleability
ability to be hammered into thin sheets
what is ductility
ability to be drawn into fine wires
what is conductivity
ability for heat or electricity to pass through
where are the metalloids found on the periodic table
along the zigzag
name some properties about the noble gases
they exist in large amounts in the atmosphere, they are chemically unreactive, they are used and glowing electric lights.
what is the process in which the atomic nuclei of unstable isotopes release fast-moving particles and energy
radioactive decay
becquerel hypothesized that uranium can
spontaneously give off energy or radiation all the time
