The periodic table

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Lesson notes

History of the Periodic Table

Early tables arranged elements by **atomic weight**, but this didn't always match properties.
In 1869, **Dmitri Mendeleev** rearranged elements so that similar properties were in the same **group**.
Mendeleev left **gaps** for undiscovered elements and predicted their properties.
When new elements were found, they matched Mendeleev's predictions.

Modern Periodic Table

Elements are arranged by increasing **atomic number** (number of protons).
Each element has a **chemical symbol** (e.g., Na for sodium).
The atomic number is written **above** the symbol.

Groups and Periods

**Columns** are called **groups**; elements in the same group have **similar properties**.
Group 1 elements are **alkali metals**; they react vigorously with water.
**Rows** are called **periods**.
Metals are on the **left** of the bold line; non-metals on the **right**.

Metals and Non-Metals

Aluminium (Al) is a **metal** (left of bold line).
Carbon (C) is a **non-metal** (right of bold line).
Metals are good conductors of electricity; non-metals are poor conductors.

Advantages of Grouping

Similar properties in a group make it easy to **predict** properties of unknown elements.
For example, all alkali metals react similarly with water.

Bohr model of sodium atom (atomic number 11) showing electron configuration 2,8,1.

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Practice questions

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1.In the periodic table, elements are arranged in order of increasing:
Easy
- Aatomic number
- Batomic weight
- Catomic radius
- Dnumber of neutrons
2.Which of the following statements about the periodic table is true?
Easy
- AElements in the same period have similar properties.
- BElements are ordered by atomic mass.
- CColumns are called groups and contain elements with similar properties.
- DMetals are found on the right of the bold line.
3.What is the atomic number of iron (Fe)?
Easy
- A26
- B56
- C55
- D30
4.Which of the following elements is a non-metal?
Easy
- AAluminium (Al)
- BCarbon (C)
- CIron (Fe)
- DCopper (Cu)
5.Why did Mendeleev leave gaps in his periodic table?
Medium
- ATo make the table look balanced
- BFor elements that had not yet been discovered
- CBecause the atomic weights did not match
- DTo separate metals from non-metals
6.Which of the following is a property of alkali metals (Group 1)?
Medium
- AThey are unreactive
- BThey react vigorously with water
- CThey are non-metals
- DThey are gases at room temperature
7.Aluminium (Al) is a metal. Which of the following best explains why aluminium is a good conductor of electricity?
Medium
- AIt is a non-metal
- BIt is a metal and metals are good conductors
- CIt is in Group 1
- DIt has a low atomic number
8.In the periodic table, what do the rows (periods) indicate?
Medium
- ASimilar chemical properties
- BNumber of electron shells
- CAtomic mass increasing
- DNumber of neutrons

More questions

9.Which of the following elements would you expect to have similar properties to sodium (Na)?
Hard
- AMagnesium (Mg)
- BPotassium (K)
- CAluminium (Al)
- DChlorine (Cl)
10.Mendeleev's periodic table was based on atomic weight, but the modern table is based on atomic number. What was a problem with ordering by atomic weight?
Hard
- AAtomic weights are not whole numbers
- BThe order of atomic weights did not always match the order of properties
- CAtomic weights change over time
- DSome elements had no atomic weight
11.Silicon (Si) is a non-metal. Which of the following is likely to be true about silicon?
Hard
- AIt is a good conductor of electricity
- BIt is ductile and malleable
- CIt is brittle and a poor conductor
- DIt reacts vigorously with water
12.Which of the following statements about the periodic table is false?
Hard
- AElements in the same group have similar properties.
- BThe periodic table is arranged by increasing atomic number.
- CAll elements in Group 1 are metals.
- DNon-metals are found on the left of the bold line.
13.Mendeleev left gaps in his periodic table. What was the reason for these gaps?
Medium
- ATo place elements with similar properties together
- BTo indicate elements that had not yet been discovered
- CTo show where the atomic weight order was broken
- DTo separate metals from non-metals
14.In the modern periodic table, elements are arranged in order of increasing:
Easy
- AAtomic mass
- BAtomic number
- CNumber of neutrons
- DRelative atomic mass
15.The atomic numbers of three elements are: X = 12, Y = 13, Z = 14. Which element is likely to be a metal?
Hard
- AOnly X
- BOnly Y
- COnly Z
- DBoth X and Y
16.A student looks at a periodic table and finds that element P has atomic number 19 and element Q has atomic number 35. Which statement about P and Q is correct?
Hard
- AP and Q are in the same period
- BP is a metal and Q is a non-metal
- CP is a non-metal and Q is a metal
- DP and Q are in the same group
17.The diagram shows a Bohr model of an atom. Which part represents the nucleus?
Medium
- AThe central dot
- BThe first shell
- CThe outermost shell
- DThe space between shells
18.The diagram shows the particle arrangement in three states of matter. Which state has particles that are far apart and move freely?
Hard
- ASolid
- BLiquid
- CGas
- DAll three
19.Which of the following pairs of elements are both in the same group?
Medium
- ALithium (Li) and Beryllium (Be)
- BCarbon (C) and Silicon (Si)
- COxygen (O) and Fluorine (F)
- DSodium (Na) and Magnesium (Mg)
20.An element has the electron configuration 2,8,2. What is its atomic number and where is it in the periodic table?
Hard
- AAtomic number 12, Period 3, Group 2
- BAtomic number 10, Period 2, Group 8
- CAtomic number 12, Period 2, Group 2
- DAtomic number 20, Period 4, Group 2
21.Which of the following is a correct statement about the modern periodic table?
Medium
- AElements are arranged by increasing atomic mass
- BThe group number tells you the number of electron shells
- CThe period number tells you the number of outer electrons
- DElements in the same group have the same number of outer electrons
22.A student measures the melting points of three elements: X = 650°C, Y = 1410°C, Z = -101°C. Which element is most likely a non-metal?
Hard
- AX
- BY
- CZ
- DCannot be determined
23.Which of the following elements would you expect to be most reactive: lithium (Li), sodium (Na), or potassium (K)?
Medium
- ALithium
- BSodium
- CPotassium
- DThey are equally reactive
24.An atom has 15 protons, 16 neutrons, and 15 electrons. What is its atomic number and mass number?
Hard
- AAtomic number 15, mass number 31
- BAtomic number 16, mass number 31
- CAtomic number 15, mass number 30
- DAtomic number 16, mass number 30
25.Which of the following is a property of non-metals?
Medium
- AThey are good conductors of electricity
- BThey are malleable
- CThey are brittle
- DThey have a shiny appearance
26.What is the chemical symbol for gold?
Easy
- AGo
- BGd
- CAu
- DAg
27.A student is given a sample of an unknown element. It is shiny, conducts electricity, and reacts vigorously with water. In which group of the periodic table is this element most likely to be?
Medium
- AGroup 1
- BGroup 7
- CGroup 0
- DGroup 4
28.Which of the following statements about the modern periodic table is correct?
Medium
- AElements in the same period have similar properties
- BElements in the same group have the same number of electron shells
- CElements are arranged in order of increasing atomic number
- DMetals are found on the right side of the bold line
29.A student wants to compare the reactivity of lithium, sodium, and potassium with water. Which experimental method would give the most valid comparison?
Hard
- AAdd equal-sized pieces of each metal to separate beakers containing the same volume of water at the same temperature and observe the reaction
- BAdd different-sized pieces of each metal to beakers of water at different temperatures and note the time for the metal to disappear
- CAdd a large piece of lithium to a small volume of water, then a small piece of sodium to a large volume of water, and compare the vigour
- DAdd each metal to acid instead of water and measure the volume of gas produced
30.In an experiment to determine the position of an unknown element in the periodic table, a student finds that the element reacts with chlorine to form a compound with formula XCl₂. In which group is element X most likely to be?
Medium
- AGroup 1
- BGroup 2
- CGroup 7
- DGroup 0
31.A student is given a sample of an unknown element. It is shiny, conducts electricity, and reacts vigorously with water. In which group of the periodic table is this element most likely found?
Hard
- AGroup 1
- BGroup 2
- CGroup 7
- DGroup 0
32.In an experiment to determine the position of an unknown element in the periodic table, a student finds that the element reacts with chlorine to form a compound with formula XCl₂. Which group is element X likely in?
Medium
- AGroup 2
- BGroup 1
- CGroup 7
- DGroup 0
33.The diagram shows the Bohr model of an atom of an element. The nucleus has 11 protons and 12 neutrons, and the electron shells contain 2, 8, and 1 electrons. Which element is this?
Hard
- ASodium
- BMagnesium
- CNeon
- DPotassium
34.In an experiment to compare the reactivity of Group 1 metals with water, a student places a small piece of lithium, sodium, and potassium each into separate troughs of water. Which additional step is most important to ensure a fair test?
Medium
- AUsing equal masses of each metal
- BUsing equal volumes of water in each trough
- CUsing the same size piece of each metal
- DUsing water at the same temperature
35.A student is given an unknown element. It is a solid at room temperature, conducts electricity, and reacts with chlorine to form a compound with formula XCl2. Using the periodic table, which element is most likely X?
Hard
- AMagnesium
- BSodium
- CAluminium
- DChlorine
36.Mendeleev left gaps in his periodic table. What did he predict about the missing elements?
Medium
- AThey would have properties similar to elements in the same group
- BThey would have atomic weights exactly between known elements
- CThey would be noble gases
- DThey would all be metals
37.In the periodic table, what does the bold staircase line separate?
Easy
- AMetals and non-metals
- BGroups and periods
- CReactive and unreactive elements
- DSolid and liquid elements
38.A student tests the electrical conductivity of three elements: X, Y, and Z. X conducts electricity, Y does not, and Z conducts electricity. Which statement about these elements is most likely correct?
Medium
- AX and Z are metals, Y is a non-metal
- BX and Z are non-metals, Y is a metal
- CX is a metal, Y is a non-metal, Z is a metal
- DAll three are metals
39.An element has the electron configuration 2,8,5. Which group and period is it in?
Hard
- AGroup 5, Period 3
- BGroup 15, Period 3
- CGroup 5, Period 2
- DGroup 15, Period 2
40.Which of the following is the chemical symbol for gold?
Easy
- AGo
- BGd
- CAu
- DAg

Revision notes

## The Periodic Table - **History**: Early tables arranged by atomic weight had problems. In 1869, **Dmitri Mendeleev** grouped elements by similar properties, leaving gaps for undiscovered elements. This created a repeating (periodic) pattern. - **Modern table**: Elements are arranged by **increasing atomic number** (number of protons). Each element has a **chemical symbol** (e.g., H for hydrogen) with atomic number above it. - **Groups**: Columns. Elements in the same group have **similar properties**. Example: Group 1 metals (alkali metals) react vigorously with water. - **Periods**: Rows. Metals are to the left of the bold line, non-metals to the right. E.g., aluminium (Al, atomic number 13) is a metal. - **Advantage**: Grouping similar properties allows **prediction** of an element's behaviour. **Key facts**: - Atomic number = number of protons. - Chemical symbol: one or two letters (first capital, second lowercase). - Metals: left of bold line; non-metals: right. - Group 1 metals = alkali metals. **Example questions**: - Q1a: False (elements in same period do not have same properties). - Q1b: False (ordered by atomic number, not atomic mass). - Q2: Iron (Fe) atomic number 26, metal; Carbon (C) atomic number 6, non-metal; Helium (He) atomic number 2, non-metal; Copper (Cu) atomic number 29, metal; Sodium (Na) atomic number 11, metal; Gold (Au) atomic number 79, metal; Oxygen (O) atomic number 8, non-metal; Silver (Ag) atomic number 47, metal. - Q3: Advantageous because it makes it easy to predict properties of elements. - Q4: Aluminium (Al) is a metal (left of bold line), so it conducts electricity; silicon (Si) is a non-metal (right of bold line), so it does not conduct well. Thus aluminium makes a better electrical wire.

Periodic table: A table of elements arranged by increasing atomic number, with elements in groups (columns) having similar properties.
Atomic number: The number of protons in an atom of an element.
Group: A column in the periodic table containing elements with similar properties.
Period: A row in the periodic table.
Chemical symbol: A one- or two-letter abbreviation for an element (first letter capital, second lowercase).
Alkali metals: The metals in group 1 of the periodic table, which react vigorously with water.
Metal: An element found to the left of the bold line in the periodic table.
Non-metal: An element found to the right of the bold line in the periodic table.

Flashcards

Who made several changes to the arrangement of the periodic table in 1869?

Dmitri Mendeleev.

What was the basis for arranging elements in early versions of the periodic table?

Atomic weight.

Why did Mendeleev leave gaps in his periodic table?

For elements that had not yet been discovered.

How are elements arranged in the modern periodic table?

By increasing atomic number (number of protons).

What is the atomic number of an element?

The number of protons that an element has.

What are the columns in the periodic table called?

Groups.

What are the rows in the periodic table called?

Periods.

What is the name of group 1 metals?

Alkali metals.

What property do alkali metals share?

They all react vigorously when placed in water.

Where are metals located in the periodic table relative to the bold line?

To the left of the bold line.

Where are non-metals located in the periodic table relative to the bold line?

To the right of the bold line.

Is aluminium a metal or non-metal?

Metal, because it is to the left of the bold line.

True or false: Elements in the same period have the same properties.

False.

True or false: In the periodic table, elements are ordered according to their atomic mass.

False. They are ordered by atomic number.

What is the chemical symbol for iron?

Fe.

What is the chemical symbol for carbon?

What is the chemical symbol for helium?

He.

What is the chemical symbol for copper?

Cu.

What is the chemical symbol for sodium?

Na.

What is the chemical symbol for gold?

Au.

What is the chemical symbol for oxygen?

What is the chemical symbol for silver?

Ag.

Why is it advantageous that elements with similar properties are in the same group?

It makes it easy to predict what properties certain elements have.

Which element is likely to make a better electrical wire: aluminium or silicon?

Aluminium, because it is a metal (left of bold line) and metals conduct electricity well.

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