eq: what can we calculate by knowing the number of each of the subatomic particles inside an atom?
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Mixtures can be separated. Into what? Other mixtures/compounds and/or
elements Compounds can be separated into
elements Can elements be separated?????
Elements are able to be subdivided into smaller and smaller particles – these are the atoms, the smallest particles that still have properties of that element
If you could line up 100,000,000 copper atoms in a single file, they would be approximately 1 cm longDespite their small size, individual atoms are observable with instruments such as scanning tunneling (electron) microscopes
What was Dalton’s explanation of atoms?
One change to Dalton’s atomic theory is that atoms are divisible into subatomic particles: Electrons, protons, and neutrons are
examples of these fundamental particles There are many other types of particles,
but we will study these three.
ParticleParticle ChargeCharge Mass (g)Mass (g) Relative Relative
MassMass
LocationLocation
Electron
(e-) -1 9.11 x 10-28 0 Electron cloud
Proton (p+) +1 1.67 x 10-24 1 Nucleus
Neutron
(no) 0 1.67 x 10-24 1 Nucleus
Atoms are composed of identical subatomic particles. (protons, neutrons, and electrons) How then are atoms of one element different
from another element? Elements are different because they contain
different numbers of PROTONS The “atomic number” of an element is the
number of protons in the nucleus The number of protons give atoms their
identity. # protons in an “atom” = # electrons
The atomic number tells you the number of protons in an atom.
If the atom is neutral then the atomic number also equals the number of electrons, because electrons dictate the charge of the atom.
Neutrons will help determine the mass of an atom. (not all atoms of the same element have the same mass)
Atomic number (Z) of an element is the number of protons in the nucleus of each atom of that element.
ElementElement # of protons# of protons Atomic # (Z)Atomic # (Z)
CarbonCarbon 66 66
PhosphorusPhosphorus 1515 1515
GoldGold 7979 7979
Mass number is the number of protons and neutrons in the nucleus of an isotope: Mass # = p+ + n0
NuclideNuclide pp++ nn00 ee-- Mass #Mass #
Oxygen Oxygen - - 1010
- - 3333 4242
- - 3131 1515
8 8 1818
Arsenic 75 33 75
Phosphorus 15 3116
•If atoms have a whole number of protons and a whole number of electrons, why do they have masses on the periodic table with decimals?•Ex: Magnesium
Mass= 24.305Protons=12Can we have 12.305 neutrons?
NO!•Number on periodic table is the atomic mass which is something slightly different from mass number.•Average atomic mass (number from the periodic table) is an average of the naturally occurring isotopes of that element. It takes into account the percent of the isotopes.
Contain the symbol of the element, the mass number and the atomic number.
X Massnumber
Atomicnumber
Subscript →
Superscript →Overall Charge
For Example:For Example:-1
Br80
35a. How many protons ? 35b. What is the mass number? 80c. How many neutrons? 45d. What is the overall charge? -1WAIT WHAAAT ??!!?!!
OVERALL CHARGE????
Discuss with your shoulder partner for 30 seconds to determine where this overall charge comes from????
Person 1 : Person with the closest birthday.
Person 2, rephrase your partner’s answer and add your response to it.
READY?
The overall charge comes from comparing the number of protons(+) to electrons(-).
If an atom has one more proton than it does electrons, it will have a +1 overall charge.
( 11 protons, 10 electrons) If an atom has two more electrons than it
does protons, it will have a -2 charge. (8 protons, 10 electrons)
Atoms that are not neutral are called IONS not ATOMS.
For Example:For Example:-1
Br80
35a. How many protons ? 35b. What is the mass number? 80c. How many neutrons? 45d. How many electrons? 36
The atomic number is the number of protons in the atom. (No two elements will have the same atomic #)
The number of protons give the atom its identity. The number of electrons give the atom the overall
charge. Very important when bonding. The mass number is calculated by adding neutrons plus
protons. Neutrons and protons make up the nucleus of the atom.
Therefore all the mass of the atom is concentrated in the nucleus.
Atoms that are NOT neutral are called IONS. (cations/anions)