Atoms And Molecules

Question 1

What is an atom

Answer 1

-Smallest unit of matter that still retains the properties of an element
-is composed of 3 subatomic particles:proton,neutron,electron

Question 2

Where are protons,neutrons,and electrons found

Answer 2

Protons and neutrons make up the nucleus of the atom, a dense and positively charged core, whereas the negatively charged electrons can be found around the nucleus in an electron cloud.

Question 3

What is the mass number

Answer 3

Number of protons+number of neutrons

Question 4

Daltons

Answer 4

-Unit off measurement used for atoms and subatomic particles aswell as molecules
-its the same as the atomic mass unit

Question 5

How many daltons are masses of neutrons and protons

Answer 5

Close to 1

Question 6

Why is mass of electron not included in the atomic mass

Answer 6

It’s only about 1/2,00 of a neutron or proton therefore it can be ignored

Question 7

Electron cloud model Schrödinger 1926

Answer 7

-Model Represents the 2 electrons as a cloud of negative charge as a result of their motion around the nucleus
-nucleons in the centre

Question 8

Bohr model 1913

Answer 8

-electrons are spheres around the nucleus
-protons have a positive charge and determine the element
-neutrons have no charge and determine the isotope

Question 9

Element

Answer 9

any substance that cannot be broken down to any other substances by chemical reactions

Question 10

Compound

Answer 10

is a substance consisting of two or more different elements combined in a fixed ratio

Question 11

Isotopes

Answer 11

-All atoms of a given element have the same number of protons, but some atoms have more neutrons than other atoms of the same element and therefore have greater mass(same number of protons but a different number of neutrons.)
-behave identically in chemical reactions

Question 12

Carbon isotopes

Answer 12

• Both 12C and 13C are stable isotopes, meaning that their nuclei do not have a tendency to lose subatomic particles, a process called decay.

• The isotope 14C is unstable, or radioactive.
A radioactive isotope is one in which the nucleus decays spontaneously, giving off particles and energy.

• When the radioactive decay leads to a change in the number of protons, it
transforms the atom to an atom of a different element.

Question 13

How is atomic mass calculated due to different isotopes

Answer 13

It’s the average of the different isotopes

Question 14

Alpha decay

Answer 14

the nucleus loses two protons.

Question 15

Beta decay

Answer 15

the nucleus either loses or gains a proto

Question 16

Gamma decay

Answer 16

no change in proton number occurs, so the atom
does not become a different element

Question 17

Radioactive Tracers

Answer 17

-used as diagnostic tools in medicine.
-The radioactive isotopes are incorporated into biologically active molecules, which are then used as tracers to track atoms during metabolism, the chemical processes of an organism.
-can be used with PET scanners to monitor growth and metabolism of cancers

Question 18

Valence

Answer 18

The bonding capacity of a given atom; the number of covalent bonds that an atom can form, which usually equals the number of unpaired electrons in its outermost (valence) shell.

Question 19

Valance electron

Answer 19

An electron in the outermost electron shell

Question 20

Valence shell

Answer 20

The outermost energy shell of an atom, containing the valence electrons involved in the chemical reactions of that atom.

Question 21

Electronic configuration

Answer 21

• An electron’s energy level is correlated with its average distance from the nucleus.
• Electrons are found in different electron shells, each with a characteristic average distance and energy level.

Question 22

Electron orbitals

Answer 22

Watch YouTube videos

Question 23

Chemical behaviour

Answer 23

• The chemical behaviour of an atom depends mostly on the number of electrons in its outermost shell.

• Atoms with the same number of electrons in their valence shells exhibit similar chemical behaviour.

-group 7 is unreactive as they have a full outer shell

Question 24

Types of chemical bonds

Answer 24

• Covalent bonds
•Electronegativity
• Ionic bonds

Question 25

Covalent bond

Answer 25

A type of strong chemical bond in which two atoms share one or more pairs of valence electrons.

Examples:h2,o2,h2o,ch4

Question 26

Electronegativity

Answer 26

The attraction of a given atom for the electrons of a covalent bond.

Question 27

Non-polar covalent bond:

Answer 27

A type of covalent bond in which electrons are shared equally between two atoms of similar electronegativity.

Question 28

Polar covalent bond

Answer 28

A covalent bond between atoms that differ in electronegativity.The shared electrons are pulled closer to the more electronegative atom, making it slightly negative and the other atom slightly positive.

Question 29

Ionic bond

Answer 29

Ionic bond: A chemical bond resulting from the attraction between oppositely charged ions.(cation and anion)

Question 30

Ions

Answer 30

An atom or group of atoms that has gained or lost one or more electrons, thus acquiring a charge.

Question 31

Weak chemical interactions

Answer 31

Hydrogen bonds
Van der waals interactions

Question 32

Hydrogen bonds

Answer 32

Hydrogen bond: A type of weak chemical bond that is formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule or in another region of the same molecule.

Question 33

Van der waals interactions

Answer 33

-are dipole-dipole interactions, which commonly exist in gases, liquids, and solids.
-3 types:

1. Dipole-dipole interactions(strongest)
2. Dipole-induced dipole interactions
3. London dispersion forces

Question 34

What are dipoles

Answer 34

are a set of separated charges within an atom/molecule

Question 35

Dipole-dipole interactions

Answer 35

are the attractive/repulsive forces that exist between two polar
molecules (molecules with a permanent dipole).

Question 36

Dipole-induced dipole interactions

Answer 36

are the attractive/repulsive forces between a polar
molecule and an atom/molecule with an induced dipole.

Question 37

London dispersion forces

Answer 37

are the attractive/repulsive forces between a nonpolar atom/molecule with an instantaneous dipole and a nonpolar atom/molecule with an induced dipole.