EQ: What can we calculate by knowing the number of each of the subatomic particles inside an atom?

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?

How can we calculate an atom’s OVERALL CHARGE?

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.

Positively charged ions are called CATIONS. Hint: Ca+ion

Negatively charged ions are called ANIONS.

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

ISOTOPIC SYMBOLSISOTOPIC SYMBOLS

-1

Br80

35

Called the Isotopic Symbol

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)

Can we say that atoms are always neutral?

What is mass number?