Chemistry: The Structure of the Atom

Democritus, Dalton, or both? Atoms cannot be destroyed.

both

Democritus, Dalton, or both? Atoms cannot be divided.

both

Steps of a nuclear reaction

1. An atom has an unstable nucleus 2. Radiation is emitted 3. The process of radioactive decay continues until the nucleus is stable 4. A stable non radioactive atom is formed

After years of studying (1.______________), Dalton was able to accurately determine the (2._______________) of the elements involved in the reactions. His conclusions resulted in the (3.____________), which helped to explain that (4.______________) in chemical reactions separate, (5.______________), or (6._____________), but are not created, (7._______________), or (8.________________).

1. Chemical reactions 2. Mass ratios 3. Atomic theory 4. Atoms 5. Combine 6. rearrange 7. Destroyed 8. Divided

Most of the area in the atom is made up of negatively charged (1.______________) traveling around the positively charged (2.______________).

1. Electrons 2. Nucleus

Dalton's atomic theory

1. Matter is composed of extremely small particles called atoms 2. Atoms are indivisible and destructible *they are divisible 3. Atoms of a given element are identical in size, mass, and chemical properties; atoms of a specific element are different of those from another element 4. Different atoms combine in simple whole-number ratios to form compounds 5. In a chemical reaction, atoms are separated combined, or rearranged

The mass of (1.__________) and (2.___________) are almost always equal to each other while the mass of the (3.______________) are really small.

1. Protons 2. Neutrons 3. Electrons

Each atom has a unique number of (1._____________). Since the overall charge of an atom is neutral the number of (2.____________) equals the number of (3.______________). *once you know the atomic number you can find the element

1. Protons 2. Protons 3. Electrons

The atoms is the (1.____________________________). When a group of atoms (2._____________) and act as a (3.________________), the result is known as a (4._______________).

1. Smallest part of an element 2. Bond 3. Unit 4. Molecule

Electron 1. Symbol: 2. Location: 3. Charge: 4. Mass:

1. Symbol: e- 2. Location: electron cloud surrounding nucleus 3. Charge: 1- or -1 4. Mass: 1/1840 amu

Neutron 1. Symbol: 2. Location: 3. Charge: 4. Mass:

1. Symbol: n, n°, n +/- 2. Location: in nucleus 3. Charge: 0 4. Mass: 1 amu

Proton 1. Symbol: 2. Location: 3. Charge: 4. Mass:

1. Symbol: p+ 2. Location: nucleus 3. Charge: +1 or 1+ 4. Mass: 1 amu

Radiation type: Alpha

1. Symbol: α 2. Mass (amu): 4 3. Charge: +2

Radiation type: Beta

1. Symbol: β 2. Mass (amu): 1/1840 3. Charge: 0

Radiation type: Gamma

1. Symbol: γ 2. Mass (amu): 0 3. Charge: 0

One atomic mass unit is ... ?

1/12 the mass of a carbon-12 atom.

atomic mass unit (amu)

1/12 the mass of a carbon-12 atom; the standard unit of measurement for the mass of atoms

Rutherfordium's atomic number is 104. How many p+ and e- does it have?

104 each

What is Neon-22 in symbolic notation?

22/10 Ne (Atomic mass/ atomic #) > Symbol

An isotope has atomic number 19 and mass number 39. How many protons, electrons, & neutrons does it have?

39-19=20 p&e= 19 n=20

The nucleus makes up about what percentage of the mass of an atom?

99.97%

nuclear reaction

A reaction in which the atom of 1 element changes into the atom of another element (transmutation)

radioactive decay

A spontaneous process in which unstable nuclei lose energy by emitting radiation

There (are/are not) instruments powerful enough to magnify atoms so that they can be seen

Are

Isotopes

Atoms with the same number of protons but different numbers of neutrons

Democritus, Dalton, or both? Different atoms combine in whole-number ratios to form compounds.

Dalton

Democritus, Dalton, or both? Different kinds of atoms come in different sizes and shapes.

Democritus

Democritus, Dalton, or both? Matter is made of empty space through which atoms move.

Democritus

Democritus, Dalton, or both? The properties of atoms vary based on shape, size, and movement.

Democritus

Both Democritus and Dalton (did/did not) suggest that matter is made up of atoms

Did

Dalton (did/did not) think that all atoms of a specific element have the same mass

Did

Dalton's atomic theory (did/did not) state that atoms of different elements combing in simple whole-number ratios to form compounds

Did

Dalton's atomic theory (did/did not) state that atoms separate, combine, or rearrange in chemical reactions

Did

Philosophers (did/did not) formulate explanations about the nature of matter based on their own experiments.

Did

Ancient philosophers (did/did not) regularly perform controlled experiments.

Did not

Dalton's atomic theory (did/did not) state that matter is mostly empty space

Did not

Democtritus (did/did not) propose that atoms are held together by chemical bonds, but no one believed him

Did not

Who determined the mass-to-charge ratio of an electron?

J.J. Thomson

Nucleus

Made of positive charged protons and neutral neutrons

To find the number of neutrons in an isotope:

Mass number - atomic number = # of n°

Electron

Negative charged fast moving particle, small mass, found in all forms of matter & moves through empty space

Neutron

Neutral, subatomic particle in an atom's nucleus that has a mass nearly equal to that of a proton

alpha particle

Particle with 2 protons and 2 neutrons emitted from a nucleus in with a 2+ charge emitted during radioactivity

Which plate do the beta particles bend toward?

Positive, they are negatively charged

Radiation

Rise in particles emitted by radioactive materials

Who calculated the mass of an electron?

Robert Millikan

Who proposed the nuclear atomic model?

Rutherford

Proton

Substance particle in an atom's nucleus that has a charge of +1 or 1+

Radioactivity

The process in which some substances spontaneously emit radiation

Atoms

The smallest unit of an element that maintains the properties of that element

Why do gamma rays not bend?

They have no charge

Dalton's atomic theory (was/was not) based on careful measurements & extensive research

Was

Dalton (was/was not) correct in thinking that atoms could not be divided into smaller particles

Was not

nuclear equation

a type of equation that shows the atomic number and mass number of the particles involved in radioactive decay

Democritus, Dalton, or both? All matter is made of tiny pieces.

both

Democritus, Dalton, or both? Atoms cannot be created.

both

specific

characterized by precise formulation or accurate restriction

isotope notation

element name- atomic mass

beta particle

fast moving electron with a -1 charge emitted by radioactive decay of substances

gamma rays

high energy radiation that has no charge and no mass and is not deflected by electronic or magnetic fields

nuclear notation

mass # (protons and neutrons)/ atomic # (protons) then followed by element symbol

cathode ray

radiation that originates from the cathode and travels to the anode of a cathode-ray tube

alpha radiation

radiation that was deflected toward the negatively charged plate *alpha particles are large particles

beta radiation

radiation that was deflected toward the positively charged plate

atomic number

the number of protons in an atom

atom

the smallest part of an element that retains all properties of that element

mass number

the sum of the number of neutrons and protons in the nucleus

atomic mass

the weighted average of the masses of the isotopes of an element

The mass of an electron is ... ?

• smaller than the mass of a proton • smaller than the mass of a neutron • a tiny fraction of the mass of an atom