physical science: atomic structure

atom

the smallest unit of an element that still has the properties of that element

proton

positive particle in the nucleus

ex: identity

neutron

neutral particle in the nucleus with protons

ex: mass

electron

negative particle outside of the nucleus in the electron cloud

ex: bonding

valence electrons

eelctrons located in the outermost energy lvl

have the most energy

quarks

make up protons and neutrons

they have a strong attraction which is what holds the nucleus together

atomic number

tells the number of protons in an atom of the element

used to identify an element

mass number

tells the number of protons and neutrons in the nucles of an atom

isotope

atoms of the same element with different numbers of neutrons

(adding or subtracting neutrons)

ion

a charged atom

atoms of the

element with different numbers of electrons

average atomic mass

weighted avg of all of the different versions (isotopes) of an element

groups

period trends

reactivity

periods

main contributors to atomic theory and their contriution

Bohr- negative electrons surrounding positive nucleus of an atom

Rutherford- positive charges in the nucleus 

Dalton- atoms of the same element are identical 

Democritus- atoms are building blocks of all matter 

Thomson- 1st discovered electrons 

difference between bohr model and electron cloud model

The Bohr model treats electrons like planets orbiting a sun in flat, fixed rings, while the electron cloud model treats electrons as waves moving through 3D zones of probability

subatomic particles: proton

positive particle in nucleus

• identity

subatomic particles: neutron

neutral particles in the nucleus w protons

• mass

subatomic particles: electrons

negative particle outside of the nucleus in the electron cloud

• bonding behavior

structure of the electron cloud, where are valence electrons located and which electrons have most energy.

• The nucleus is in the center made of protons and neutrons and the the space surrounding the nucleus is the electron cloud filled with electrons 

• Valence electrons are in the outermost layer and have most energy

where is the mass and volume of the atom are

• The mass is in the nucleus 

• The volume is in the electron cloud 

describe the forces that hold an atom together

• Electromagnetic force, the attraction between the nucleus and electron cloud holds the atom together 
  
  

what does it mean for an atom to be electrically neutral

The protons equal the number of electrons

what does it mean for an atom to be not electrically neutral

difference between mass number and avg atomic mass

• Mass number: tells the number of protons and neutrons in the nucleus of an atom 

• Avg Atomic mass: weighted average of all the different isotopes of an element

what two isotopes of the same element have in common and what if diff

Atomic # is the same for both, mass # is different

1st 20 periodic table elements