Chemistry: ATOMS, ELEMENTS AND COMPOUNDS

Question 1

what is a physical property?

Answer 1

is a characteristic of a substance that can be observed or measured without changing the identity of the substance.

examples of physical properties

color, hardness, melting and boiling points

Question 2

What is a chemical property?

Answer 2

is a characteristic of a particular substance that can be observed in a chemical reaction.

examples of chemical properties

flammability, toxicity, combustion.

Question 3

Qualitative properties

Answer 3

are observed by senses. Examples are color, state, brittleness,

Question 4

quantitative properties

Answer 4

a property of a. substance that is measurable for example, height, weight temperature, melting point, boiling point.

Question 5

What is matter

Answer 5

Matter is anything that takes up space

Question 6

Physical changes

Answer 6

In a physical change the appearance changes but the kind of matter in the substance does not.

boiling point, melting point

Question 7

chemical changes

Answer 7

in a chemical change the kind of matter changes and one or more new substances with new properties is formed.

examples

combustion

Question 8

what is the difference between A pure substance and a mixture?

Answer 8

a pure substance consists only of one element or one compound. a mixture consists of two or more different substances.

example of a pure substance
Oxygen

example of a mixture
sea water

Question 9

what is the difference between a mixture and a solution?

Answer 9

In a mixture, substances are generally just mixed and are not completely dissolved. In a solution, substances are dissolved completely and they cannot be filtered out.

Question 10

what is an element?

Answer 10

a pure substance that cannot be broken down into a simpler chemical substance.

example: Oxygen

Question 11

what is a compound?

Answer 11

a pure substance composed of 2 or more different elements that are chemacly joined.

example: table salt

Question 12

what is a molecule and how does it relate to a compound?

Answer 12

a molecule is a group of atoms bonded together

Question 13

what is an atom and how does it connect to elements?

Answer 13

An atom is the part of an element.

Question 14

what are the 7 diatomic elements

Answer 14

hydrogen (H), nitrogen (N), oxygen (O), fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

Question 15

characterize non metals.
and where are they located on the periodic table?

Answer 15

a non metal is usually a gas or a dull powdery solid that does not conduct heat or electricity.

non metals are located on the right side of the staircase except for hydrogen witch is located in the top left corner.

Question 16

Characterize metals.
and where are they on the periodic table?

Answer 16

Metals are lustrous, malleable, ductile, good conductors of heat and electricity.

The metals are located on the left side of the stair case.

Question 17

charactorize metaloids.
and where are they on the periodic table?

Answer 17

metalloids are elements that has properties of both metals and non metals

metalloids are located on the staircase.

Question 18

what are groups on the periodic table and how are they significant?

Answer 18

they are the vertical column of the periodic table that signifies the number of valence electrons in an element.

Question 19

what are periods on the periodic table and how are they significant?

Answer 19

are the the horizontal rows in the periodic table that signify the number of electron shells in an element.

Question 20

what are alkali metals?

Answer 20

an element in group 1 of the periodic table.

Question 21

what are alkali earth metals?

Answer 21

n element in group 2 of the periodic table.

Question 22

what are nodal gasses?

Answer 22

an element in group 18 of the periodic table.

Question 23

what are halogens?

Answer 23

an element in group 17 of the periodic table.

Question 24

what are similarities between alkali earth metals, alkali metals?

Answer 24

Alkali metals and alkaline earth metals have the following properties: They are relatively soft metals. They are relatively low density metals. They have relatively low melting points

Question 25

what are the similarities between nodal gasses and halogens?

Answer 25

they are all non-metallic elements

Question 26

Define Atomic Number

Answer 26

The atomic number is given in the top left hand corner on each element on the periodic table.

The atomic number is the number of protons in an atoms nucleus

Question 27

Define Atomic Mass

Answer 27

Atomic mass is the mass of an atom in atomic mass units (U).

Question 28

Define Mass Number

Answer 28

The number of protons and neutrons in an atoms nucleus.

Question 29

how do you use the atomic number and mass number to calculate the number of neutrons in an atoms of a given element?

Answer 29

To calculate the number of neutrons in an atom of a given element, you subtract the atomic number from the mass number.

Question 30

Define isotope.

Answer 30

an isotope is an atom with the same number of protons but a different number of neutrons.

Question 31

What is the connection between isotopes and the calculation of the average atomic mass of an element?

Answer 31

Isotopes are different forms of an element. The average atomic mass of an element takes into account the masses of its isotopes and how common they are. It is a weighted average based on the abundance of each isotope.

Question 32

Name the first 20 elements on the periodic table and what are there symboles.( you are allowed to look at the periodic table

Answer 32

1. Hydrogen (H)
2. Helium (He)
3. Lithium (Li)
4. Beryllium (Be)
5. Boron (B)
6. Carbon (C)
7. Nitrogen (N)
8. Oxygen (O)
9. Fluorine (F)
10. Neon (Ne)
11. Sodium (Na)
12. Magnesium (Mg)
13. Aluminum (Al)
14. Silicon (Si)
15. Phosphorus (P)
16. Sulfur (S)
17. Chlorine (Cl)
18. Argon (Ar)
19. Potassium (K)
20. Calcium (Ca)

Question 33

Define the term valence electron.

Answer 33

A valence electron is an electron found in the outermost shell of an atom. It plays a crucial role in the atom’s chemical behavior and bonding with other atoms.

Question 34

how do you determine the number of valence electrons for any of the group or representative elements.

Answer 34

To determine the number of valence electrons for an element, you generally look at the group number in which the element is located on the periodic table.

for example
an element in group 1 would have 1 valence electron and an element in group 14 would have 4 valence electrons.

Question 35

definition of ion

Answer 35

An ion is a particle with a positive or negative charge, which is formed by the loss or gain of electrons in an exchange reaction.

Question 36

definition of anion

Answer 36

An anion is an ion with a negative charge, meaning it has more electrons than protons.

Question 37

definition of cation

Answer 37

Cations are positively charged ions. They are formed when a metal loses its electrons.

Question 38

what is the octet role

Answer 38

The octet rule refers to the tendency of atoms to prefer to have eight electrons in the valence shell. When atoms have fewer than eight electrons, they tend to react and form more stable compounds.

Question 39

distinguish between ionic and molecular compounds.

Answer 39

As a general rule of thumb, compounds that involve a metal binding with either a non-metal or a semi-metal will display ionic bonding.

example

Compounds that are composed of only non-metals or semi-metals with non-metals will display covalent bonding and will be classified as molecular compounds.

example

Question 39

distinguish between ionic and molecular compounds.

Answer 39

Ionic compounds are made of metals and nonmetals. Compounds composed of metals and non-metals contain charged species.

example
Table salt

Molecular (or covalent)compounds are made of nonmetals.

example
water