-discovered the universe seemed to be expanding from a central point origin of the bigbang theory. -shine with light shifted toward the red end of the visible spectrum.

occurs because the light waves of cosmic bodies are stretched into low-frequency red waves as they move away from an observer on earth.

within the 1st and 2nd after the explosion, subatomic particles were formed.

most abundant elements in the universe

processes in which a nucleus either combines with another nucleus or splits into smaller nuclei.

combine

splits

processes involve the emission of energetic particlesof an atom

results in the emission of a particle

produces a daughter involves with a mass number that is lower by 4 and an atomic number that is lower by 2 than the parent nucleus

converts a neutron to a proton and emits a high-energy electron, producing a daughter nucleus with the same mass number as the parent and an atomic number that is higher by 1

a daughter nucleus in nuclear excited state undergoes a transition to a lower-energy state by emitting y rau

from the high frequency and of the electromagnetic spectrum

have no mass

according to him there were only 4 elements— fire, air, water, and earth that make up matter.

hera rules what?

hades rules what?

zeus rules what?

Persephone rules what?

made the 1st recorded suggestion that matter consists of seperate particles

he conceived the idea that atoms are indivisible units which diffwr in size and shape.

atomism (from the greek atomon "uncuttable"," indivisible ") is a natural philosophy that developed in several ancient traditions

the atomists that nature consists of two fundamental principles: atom and void

what are the 2 fundamental principles that leucippus theorized that nature consist of?

considered all matter to be made up of tiny discrete, indivisible, and indestructible fundamental units of matter called atoms (from greek word atomos, which means uncuttable)

-named the smallest piece of matter "atomos" / not to be cut - atoms were infinite in number, always moving and capable of joining together -atoms were snakl hard particles made the same material but different shapes and sizes

proposed that all matter was continuous and can be further divided infinitely into smaller pieces.

in the 17th and 18th centuries, he formulated rhe atomic theory that maked the beginning of the modern era of chemistry

arw composed of atoms of more than one element

all atoms are made up of what?

represented that electrons have a negative charge

he proposed the "plum pudding"

he discovered the electron

he was the 1st scientist to show the atom was made of even smaller things

he used cathode ray tube to discover electrons

using a cathode ray tube to discovered canal rays which are beams of positively charged particle

he credited with the discovery of protons in an atom

determined the charge on an electron. used thomson's charge to mass ratio to calculate the mass of an electron

he used gold foil experiment, showed another view on yhe the structure of the atom

-he discovered the nucleus in atom. -there is a small, dense center with a positive charge. -atom is mostly empty space.

a small, dense core with a positive charge

observe that electrons don't radiate energy as they circle the nucleus -lowest energy is found in ghe smallest orbit. -radiation is absorbed or emitted when an electron moves from one orbit to another

quantum mechanical modelin 1920,which treats electron as matter waves

the father of modern quantum theory -atoms were arranged as "layers with layers" or in a cloud or space.

proved that presence of neutral subatomic particles, which he named neutrons.

-joseph john thomson. -negatively charged particles. -spin so fast that it can be difficult for scientist to observe them.

they are attracted to the positive charge of the protons and are the smallest particles in an atoms you can fet 2000 of them into a proton.

-ernest rutherford. -positively charged particles in the nucleus of an atom.

the mass of it is the same as a neutron but 1840x greater than the mass of electron.

-james chadwick. -electrically neutral, they can go deep into matter. -it has no electric charge. -located in the nucleus of atom. -microscopically magnetic, they can show magnetism.

created as rhe originator of the 1st successful theory of chemical bonding

-is an outer shell electron that is associated with an atom. -can be gained ot lost during a chemical reaction.

-are diagrams that show the number of valence electron of a particular element with dots that represent lone pairs. -do not visualize the elctrons in the inner principal energy levels

sharing of electrons, forming non polar and polar covalent bond

with equal sharing of electrons is called?

sharing unequal electron is called?

is the relative ability of an atom in the bonded state of attract electrons