Atoms and Elements Review Packet Answer Key

NGSS Chemistry 2024-2025

What did John Dalton study

• studied ratios in which elements combine in chemical reactions

Theory about atoms

• all elements are composed of tiny indivisible particles called atoms

• atoms of the same element are identical; atoms of different elements are different

• atoms of different elements combine in whole-umber ratios to form compounds

  • atoms of one element cannot be changed into atoms of another element through chemical means

J.J. Thomson discovered?

• discovered cathode rays (electrons)

J.J. Thomson performed?

• performed experienments that involved passing electric current through gases at low pressure

Who created plum pudding model of atoms

J.J. Thomson

What is plum pudding model of atom

atoms were solid with positive and negatives charges equally dispersed

Gold foil experiment, who?

Ernest Rutherford
gold foil experiment → shot alpha particles at gold foil

Ernest Rutherford concluded…

• most alpha particles went through the gold foil and some were deflected

  • concluded that the atom was made up of mostly empty space except for a small, dense, positively charged center (nucleus)

Who made planetary model of the atom and what is it about

• Neils Bohr

  • electrons arranged in concentric circles around the nucleus

Neils Bohr discovered ?

• electrons in a particular path have a fixed energy, so the electron will not fall into the nucleus

Who made quantum mechanical model of atom and what is it about

• Irwin Schrodinger

• quantum mechanical model of the atom - only the probable location of an electron can be determined

Irwin Schrodinger used what

• used quantum theory to solve a mathematical equation describing the location and energy of an electron in a hydrogen atom

describe how the periodic table is arranged

• arranged by increasing atomic number

  • elements in the same group/family exhibit similar physical and chemical properties

periodic law

• when elements are arranged in order of increasing atomic number, there is a periodic repetition of the physical and chemical properties

describe metals

• siny

• conduct heat and electricity

• ductile

  • malleable

describe alkali metals

• shiny

• most reactive metals

• not found freely in nature

• soft, can be cut with a knife

• soluble in water

• rapid reactions with oxygen and water

describe alkaline earth metals

• gray-white luster

• less reactive than alkali metals

• harder than alkali metals

• less soluble in water

• less reactive than alkali metals

describe transition metals

• exhibit typical metallic properties (ductile, malleable, luster, good conductors of heat and electricity)

describe metalloids

• elements with properties of both metals and nonmetals

describe nonmetals

• non lustrous

• poor conductors of heat and electricity

describe halogens

• very reactive (fluorine most reactive nonmetal)

• not found freely in nature

describe noble gases

• unreactive

electromagnetically, ionization energy, atomic radius