periodic Table

Question 1

matter

Answer 1

Anything that has mass, all objects have matter.

Question 2

atoms.

Answer 2

The basic building blocks of all matter, can combine to form molecules but cannot be divided into smaller parts by ordinary chemical means.

Have the same number of protons as electrons so the whole atom has no electric charge.

Question 3

element

Answer 3

A substance made up of only 1 type of atom, each with the same number of protons.

Question 4

structure of the atom- nucleus, electrons, protons, neutrons.

Answer 4

Nucleus is surrounded by orbiting electrons which are negatively charged and arranged in shells.

The nucleus, the center of the cell, contains protons which are positively charged and neutrons which are negatively charged.

Protons have the same mass as neutrons.

Question 5

Atomic particle, relative mass and relative charge.

Answer 5

Proton, 1, +1
Neutron,1,0
electron,1/1840,-1

Question 6

History of the atom, model dalton

Answer 6

Dalton’s Model (1803)

Proposed the atom as a solid, indivisible sphere.
Atoms of different elements vary in mass and properties.
Introduced the concept of chemical compounds formed from atoms.

Question 7

History of the atom, model Thomsons

Answer 7

Thomson’s Model (1897)

Discovered the electron through cathode ray experiments.
Proposed the “Plum Pudding Model,” suggesting atoms are spheres of positive charge with embedded electrons.
Introduced the idea of subatomic particles.

Question 8

History of the atom, model Rutherford.

Answer 8

Rutherford’s Model (1911)

Conducted the gold foil experiment, revealing a dense, positively charged nucleus.
Proposed that electrons orbit the nucleus, leading to the “Nuclear Model” of the atom.
Introduced the concept of empty space within the atom.

Question 9

History of the atom, Bohr.

Answer 9

Bohr’s Model (1913)

Built on Rutherford’s model by introducing quantised energy levels for electrons.
Suggested electrons move in fixed orbits around the nucleus with specific energy levels.
Explained atomic spectra and stability of electron orbits.

Question 10

Benefits of models in science.

Answer 10

Makes complex things easier to understand.
Provides clear visual representations.
Helps predict outcomes and guide experiments.
Aids in experimental design and variable identification.
Useful across various scientific fields.

Question 11

Limitations of models in science.

Answer 11

Can lead to inaccuracies.
Rely on assumptions that may not always hold true.
May become outdated with new data.
Choice of model can introduce bias.
Often miss key variables and interactions.

Question 12

Atoms of different elements differ in num. of protons (atomic number)

Answer 12

The atomic number of an element tells the number of protons in the nelcused of that element.

e.g. lithium atomic number = 3, nitrogen atomic number =7

Question 13

Use periodic table to determine atomic number

Answer 13

The atomic number, or number of protons is the bottom of the two numbers next to the symbol.

Question 14

Use periodic table to determine mass number

Answer 14

The mass number which is the number of protons and neutrons is the top number next the symbol.

Question 15

Use periodic table to determine the element symbol.

Answer 15

The symbol of the element is the letters on the periodic table.

Question 16

Use mass and atomic number to determine number of neutrons.

Answer 16

Number of protons is the atomic number.

So its the mass number minus the atomic number for the amount of neutrons.

Question 17

draw diagrams to represent the nuclear and electronic configuration for the
first 20 elements., how to make them.

Answer 17

Electrons are arranged in shells around the nucleus.

Electrons fill the first shell, then second then third and so on.

First shell can fit 2, the second 8, the third 18 and the fourth 32.

Calculated using the formula 2n squared, n the number of the electronic shells.

Number of electrons are the same as the number of protons, which is the atomic number so the atomic number will also tell the amount of electrons.

Question 18

Position of metals and non-metals on periodic table

Answer 18

First 100 elements are arranged in order of increasing atomic number.

Then arranged in row so elements with similar properties are in the same column.

Metals can be found mainly in Groups 1 and 2 in the central block. And non metals in groups 7 and 8.

Question 19

identify the names of some of the
chemical groups on the Periodic Table

Answer 19

Group 7: Halogens
Characteristics:
Have 7 electrons in their outer shell.
Reactivity decreases down the group as the outer electrons get further from the nucleus.
Examples: Fluorine (F), Chlorine (Cl), Bromine (Br).

Group 8: Noble Gases
Characteristics:
Have full outermost shells (8 electrons, except Helium which has 2).
Extremely stable and do not need to gain or lose electrons, making them largely unreactive.
Examples: Helium (He), Neon (Ne), Argon (Ar).

Alkali Metals (Group 1)

Characteristics: Highly reactive, especially with water; soft metals; have one valence electron.
Examples: Lithium (Li), Sodium (Na), Potassium (K).

Question 20

What is ionic bonding.

Answer 20

• where electrons completely transfer.
• occurs between metals and non-metals
• involves a transfer of electrons form one atom to another to form electrically charged “atoms” called ions.
• each with a complete outer electron shell, so very unreactive like nobel gasses.

Question 21

Example of Ionic Bonding

Answer 21

e.g. Sodium and Chlorine to form sodium chloride.

• sodium has one electron in its outer shell
• transfers to chlorine atom, both have now 8 electrons in the outer shell.
• now the atoms are ions and NaCI.

Question 22

Properties of Ionic Bonding.

Answer 22

• high melting points
• conduct electricity when molten or in a soluction bc the charged ioins and free to move around.
  sometimes dissolve in water
  crystalline.

Question 23

What is covalent bonding.

Answer 23

• When two nonmetals combine, the atoms share electrons resulting in the formation of a covalent bond and a covalent compound.
• The idea of stability is the same, resulting when each atom has eight
  elecgrons in its outermost orbit.

-results in formation of molecules

Question 24

Examples of covalent bonding.

Answer 24

e.g. fluorine reacting with fluorine to form fluorine gas.
- When they meet they share one electron with each toerh, so there are 8 in its outermost orbit, stable molecule (diatomic molecule) is formed.
- contains 2 fluorine atoms joined together by a single covalent bond(formed when one pair of electrons is shared)
-valency is still 1.

Question 25

what is valency.

Answer 25

• the outermost shell of the aotm is the valence shell, it becomes stable when there are 8 electrons
  -the valency of an element indicates the numver of its electrons involved in forming chemical bonds.

Question 26

Describe how to determine valencies of ions from the periodic table

Answer 26

-Across a period, valency goes to 4 then down to 0.
- going down a group, Valency remains the same.
Group 1 (Alkali Metals): Valency = +1
Group 2 (Alkaline Earth Metals): Valency = +2
Group 13 (Boron Group): Typically forms +3 ions
Group 14 (Carbon Group): Typically forms +4 or
Group 15 (Nitrogen Group): Typically forms -3 or
Group 16 (Chalcogens): Typically forms -2
Group 17 (Halogens): Valency = -1
Group 18 (Noble Gases): Usually do not form ions (inert).

Question 27

Properties of covalent bonds

Answer 27

• attraction between molecules is stron, covalent bond is weak.
• low melting and boiling point.
• no overall electric charge, cannot conduct electricity.

Question 28

Valency for polyatomic ions, hydroxide

Answer 28

Hydroxide (OH−)

Valency: -1
Composition: One oxygen atom and one hydrogen atom.

Question 29

Valency for polyatomic ions, Nitrate

Answer 29

Nitrate NO 3-

Valency: -1
Composition: One nitrogen atom and three oxygen atoms.

Question 30

Valency for polyatomic ions, Carbonate

Answer 30

Carbonate CO 32-
,
Valency: -2
Composition: One carbon atom and three oxygen atoms.

Question 31

Valency for polyatomic ions, Sulfate

Answer 31

Sulfate, SO 42- )2

Valency: -2
Composition: One sulfur atom and four oxygen atoms.

Question 32

Balancing ionic compounds.- there is another diagram

Answer 32

step 1 identify the cation or anion
- cation is usually a metal and positively charged ion.
- anion is usually non-metal and negatively charged.

Step 2 identfy the chrage,if it doesn;’ts day on periodic table memorise.

Step 3:
balance the charges
- total positive charge has to equal the total If the charges are the same, +1,-1 then just write the element names
- if different then add/minus ions e.g. Cr3++n3–>Cr3N3->CrN

Question 33

Name ionic compounds given their chemical formula.

Answer 33

if the cation has a fixed charfe then use the elemental name
- if the cation has multiple charges i.e fe2+ then specify the charge with roman numerals (ll)
- for single element anion is use “ide”
- for polyatomic ions use the name of the ion directly.

Question 34

Identiy that salt is a compound consisting of a metal ion and a non-metal or polyatomic ion.

Answer 34

• Metal ion: derived from the base.
  -non-metal/polyatomic: ion derived from an acid. and Polyatomic ions can include gorups of atoms carrying a charge.

-Salts are ionic compounds.
- in salt the total positive charge from metals must = tota; negative charge from the non-metal to create a balance.

e.g. sodium chloride(NaCI)
1 Na+ balanced CI- to form a neutral salt, or compound.

Question 35

Name covalent compounds given their chemical formulae.

Answer 35

1: the name of the first element should be given in full.
2: add mon, di, tri, tetra, penta, hexa, hepta, octa, nona, deca to indicate how many atoms of the 2nd molecude.
3: name of the 2nd element is shortened “ide” is added to shorten the name.

e.g. N2O5 ( Dinitrogen Pentoxide)

Question 36

Write covalent compounds given their name

Answer 36

1:Write the symbol of the first element.

2: If there is a prefix, add the corresponding subscript.

3:Write the symbol of the second element, adding its subscript according to its prefix.

e.g.Dinitrogen Tetroxide

Identify elements: Nitrogen (N) and Oxygen (O).
Use prefixes: “Di-“ means 2 for nitrogen, and “Tetra-“ means 4 for oxygen.
Write the formula: N2O4