Atoms and Subatomic Particles

Question 1

What is an atom?

Answer 1

The smallest unit of an element that consists of subatomic particles (protons, neutrons, electrons)

Question 2

What is the inner part of an atom called?

Answer 2

The nucleus
- it has positively charged protons and uncharged neutrons
- protons and neutrons give mass to the atom

Question 3

What determines an element?

Answer 3

The number of protons (the atomic #)

Question 4

What charge do electrons have?

Answer 4

Electrons (e-) have a negative charge
- electrons spin around the nucleus in an electron cloud

Question 5

What makes an atom electrically neutral?

Answer 5

When the # of protons = the # of electrons
- remains the same unless an atom gains or loses an electron

Question 6

What does the atomic number mean?

Answer 6

• the atomic number is the same number of protons in the nucleus
• an atom of carbon is unique to carbon, but a proton is not
  - one proton is the same as any other proton
  - same goes for neutrons and electrons
  - the difference in elements is determined by the
  unique number of protons is has

Question 7

How many protons does Carbon have?

Answer 7

Carbon has 6 protons, and its atomic number is 6

Question 8

How many protons does Hydrogen have?

Answer 8

Hydrogen has 1 proton, and its atomic number is 1

Question 9

What does the atomic number identify?

Answer 9

• the number of protons
• the number of neutrons
• the usual number of electrons in an element

Question 10

What is the mass number?

Answer 10

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

Question 11

What is Carbon’s mass number?

Answer 11

Carbon’s mass number is about 12 because it has 6 protons and 6 neutrons

Question 12

Tell me about what is shown about Helium on the periodic table.

Answer 12

Atomic number: 2
Proton number: 2 (positively charged)
Neutron number: 2 (neutrally charged)
Z number: 2
Symbol: He
Atomic mass number: 4

Question 13

What are isotopes?

Answer 13

• different versions/types of an element
• each element can exist as different isotopes
• they each have different numbers of neutrons

Question 14

Give an example of isotopes

Answer 14

Carbon has 6 protons and 6 neutrons. This is C12. C13 or C14 are heavy isotopes. They have one or two more than the standard number of neutrons. C13 has 7 neutrons, C14 has 8 neutrons.

Question 15

What are radioisotopes?

Answer 15

These are heavy isotopes that are unstable (radioactive)
- the nucleus can decay and give off subatomic particles, releasing electromagnetic energy

Question 16

What is a half-life?

Answer 16

Time for half of an isotope to decay
- exposure can damage cell (birth defects or cancer)

Question 17

What are electron shells?

Answer 17

Electron shells are layers of electrons that surround the nucleus at distinct energy levels
- there are 1 to 5 electron shells

Question 18

How many electrons does each electron shell hold?

Answer 18

• the first one only holds 2 electrons
• all the other 4 can hold 8 electrons

Question 19

What is the valance shell?

Answer 19

• the outermost shell
• it tells you whether it is likely to participate in a chemical reaction with other atoms
• this is because of the octet rule

Question 20

What is the octet rule?

Answer 20

An atom will gain or lose an electron to have a full or balanced valance shell (have 2 in the valance shell or 8 in the valance shell).

Question 21

What is the function of an electron shell?

Answer 21

Atoms don’t exist as independent entities, they are constantly in chemical reactions with other atoms to form compounds or to break down into smaller compounds
- function is to participate in chemical reactions with other atoms to create compounds

Question 22

How are compounds made from elements?

Answer 22

• elements with valance shells are inert
• element with unstable (not full) valance shells are moving around to make their valance shell stable
  ex. - H needs 1 electron
  - O needs 2 electrons
  - 2 H bond to O
  - this forms H2O