Atomic Structure And The Periodic Table

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टीचर्स के लिए: Atomic Structure And The Periodic Table (Co-ordinated Sciences (Double Award) [CIE], Chemistry) के लिए इस्तेमाल के लिए तैयार लेसन स्लाइड्स, रिवीज़न नोट्स, डायग्राम — इन्हें अपने लेसन में इस्तेमाल करें, या टॉपिक को एक इंटरैक्टिव क्लास एक्टिविटी की तरह चलाएं जिसे आपके स्टूडेंट्स लाइव गेम की तरह खेलें।

लेसन नोट्स

Elements, Compounds & Mixtures

An element is a substance made of atoms with the same number of protons; it cannot be split chemically.
A compound is a pure substance of two or more elements chemically combined; it cannot be separated by physical means.
A mixture is a combination of substances not chemically combined; it can be separated by physical methods like filtration or evaporation.
Examples: element – oxygen; compound – carbon dioxide (CO₂); mixture – sand and water.

Particle diagram showing elements, compounds and mixtures

Atomic Structure

Atoms consist of a nucleus (protons + neutrons) surrounded by electrons in shells.
Protons have relative mass 1 and charge +1; neutrons have mass 1 and charge 0; electrons have negligible mass and charge –1.
The atomic number (Z) is the number of protons; it defines the element.
The mass number (A) is the total number of protons + neutrons.
Number of neutrons = mass number – atomic number.
In a neutral atom, number of electrons = number of protons.

The structure of an atom

Electronic Configuration

Electrons fill shells in order: first shell holds 2, second holds 8, third holds 8 (simplified model).
The electronic configuration is written as numbers separated by commas, e.g., carbon is 2,4.
The number of occupied shells equals the period number; the number of outer electrons equals the group number (for Groups I–VII).
Elements in the same group have the same number of outer-shell electrons.
Noble gases have full outer shells and are unreactive.

A simplified model showing the electron shells

Isotopes

Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons.
They have the same chemical properties because they have the same electron arrangement.
Physical properties (e.g., density, melting point) may differ due to different masses.
Example: carbon-12 (⁶ protons, ⁶ neutrons) and carbon-14 (⁶ protons, ⁸ neutrons).

The structure of a hydrogen-2 (deuterium) atom

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साइन अप करें — फ्री लॉग इन

प्रैक्टिस सवाल

फ्री प्रीव्यू — 53 में से 8 सवाल। सभी देखने के लिए साइन अप करें।

1.Which of the following is a pure substance made up of two or more elements chemically combined?
Easy
- AElement
- BCompound
- CMixture
- DSolution
2.What is the relative mass of a proton?
Easy
- A0
- B1
- C1/1840
- D2
3.The atomic number is the number of protons in the nucleus of an atom.
Easy
True or false?
4.What is the electronic configuration of a neutral magnesium atom?
Easy
5.An atom of element X has atomic number 29 and mass number 63. How many neutrons does it have?
Medium
- A31
- B37
- C40
- D34
6.Complete the sentence:
Easy
Isotopes are atoms of the same element that have the same number of protons but a different number of ____.
7.Match each subatomic particle to its charge.
Easy
- Proton
- Neutron
- Electron
- 1+
- 0
- 1-
8.Arrange the following elements in order of increasing atomic number: chlorine, sodium, carbon, calcium.
Easy
- Carbon
- Sodium
- Chlorine
- Calcium

और सवाल

9.Which of the following elements has the electronic configuration 2,8,8,2?
Medium
- AArgon
- BPotassium
- CCalcium
- DScandium
10.What is the name of the group of elements that have a full outer shell of electrons and are unreactive?
Easy
11.The diagram shows a Bohr model of a carbon atom. What does the small red circle at the centre of the diagram represent?
Easy
- AThe nucleus
- BAn electron shell
- CA single electron
- DThe chemical symbol label
12.In the diagram of a sodium atom shown, how many electrons are in the third shell?
Easy
13.Which of the following substances is an element?
Easy
- ACarbon dioxide
- BIron
- CWater
- DSalt
14.A compound can be separated into its elements by physical methods such as filtration.
Easy
True or false?
15.What is the charge of a neutron?
Easy
- A+1
- B0
- C-1
- D+2
16.An atom has 11 protons and 12 neutrons. What is its mass number?
Easy
- A11
- B12
- C23
- D1
17.What is the electronic configuration of a neutral sulfur atom?
Medium
- A2,8,6
- B2,8,8
- C2,6,8
- D2,8,2
18.An element has electronic configuration 2,8,8,2. Which group is it in?
Medium
- AGroup 2
- BGroup 8
- CGroup 18
- DGroup 1
19.Isotopes of the same element have the same number of protons but different numbers of neutrons.
Easy
True or false?
20.Which statement about isotopes is correct?
Medium
- AIsotopes have different chemical properties because they have different numbers of electrons.
- BIsotopes have the same chemical properties because they have the same number of outer electrons.
- CIsotopes have different physical properties because they have different numbers of protons.
- DIsotopes have the same physical properties because they have the same number of neutrons.
21.The diagram shows a Bohr model of an atom. What do the concentric rings drawn around the centre represent?
Easy
- AElectron shells
- BNeutron paths
- CIsotope boundaries
- DMolecular bonds
22.Match each subatomic particle to its relative mass.
Easy
- Proton
- Neutron
- Electron
- 1
- 1/1840
- 1
23.Which of the following statements about isotopes are correct? (Select all that apply)
Medium
- AIsotopes have the same number of protons.
- BIsotopes have the same number of neutrons.
- CIsotopes have different mass numbers.
- DIsotopes have the same chemical properties.
- EIsotopes have different numbers of electrons.
24.A sample of a substance is analysed. It is found to contain only one type of atom. Which type of substance is it?
Easy
- AElement
- BCompound
- CMixture
- DAlloy
25.The relative mass of an electron is approximately 1/1840 of a proton.
Easy
True or false?
26.A neutral atom has 17 electrons. How many protons does it have?
Easy
- A17
- B18
- C35
- DNot enough information
27.The diagram shows a Bohr model of a sodium atom. How many neutrons does the nucleus contain, according to the diagram?
Easy
- A11
- B12
- C23
- D1
28.Which of the following statements about the noble gases are correct? (Select all that apply)
Medium
- AThey have full outer shells of electrons.
- BThey are very reactive.
- CThey are found in Group 8/0 of the Periodic Table.
- DThey have the same number of electrons as each other.
29.Which of the following statements about the electronic configuration of the first 20 elements are correct? (Select all that apply)
Medium
- AThe first shell can hold a maximum of 2 electrons.
- BThe second shell can hold a maximum of 8 electrons.
- CThe third shell can hold a maximum of 18 electrons at this level.
- DThe fourth shell starts to fill after the third shell is completely full.
- EPotassium has electronic configuration 2,8,8,1.
30.In an experiment to determine the percentage of oxygen in air, a student uses a gas syringe and a heated copper tube. Which statement about the experimental method is correct?
Medium
- AThe copper reacts with oxygen to form copper(II) oxide, reducing the volume of gas.
- BThe copper reacts with nitrogen to form copper nitride, reducing the volume of gas.
- CThe copper acts as a catalyst and does not change the gas volume.
- DThe copper absorbs carbon dioxide, causing a decrease in volume.
31.A student is asked to separate a mixture of iron filings and sulfur powder. Which physical method would be most effective?
Easy
- AUse a magnet to attract the iron filings.
- BAdd water to dissolve the sulfur and filter.
- CHeat the mixture to melt the sulfur and pour off.
- DUse a sieve to separate the different sized particles.
32.Which of the following are correct statements about isotopes? (Select all that apply)
Medium
- AIsotopes of the same element have the same number of protons.
- BIsotopes of the same element have the same number of neutrons.
- CIsotopes of the same element have the same electronic configuration.
- DIsotopes of the same element have different chemical properties.
- EIsotopes of the same element have the same number of electrons in a neutral atom.
33.Arrange the following steps in order to determine the percentage of water in a hydrated salt by heating. Start with the first step.
Medium
- Record the mass of the crucible and lid.
- Heat the crucible strongly for several minutes.
- Allow the crucible to cool in a desiccator.
- Add the hydrated salt to the crucible and reweigh.
- Reweigh the crucible and contents after cooling.
34.The diagram shows a Bohr model of a neon atom. Which labelled part represents the outermost electron shell?
Easy
- AThe innermost circle around the nucleus
- BThe second circle from the nucleus
- CThe outermost circle
- DThe nucleus itself
35.An element is a pure substance made of atoms that all contain the same number of protons.
Easy
True or false?
36.Which of the following is a mixture?
Easy
- ACopper(II) sulfate
- BSulfur powder and iron filings
- CCarbon dioxide
- DCalcium carbonate
37.The relative mass of an electron is 1.
Easy
True or false?
38.Which of the following are true about isotopes? (Select all that apply)
Medium
- AThey have the same number of protons.
- BThey have different numbers of neutrons.
- CThey have the same number of electrons in a neutral atom.
- DThey have different chemical properties.
- EThey have the same mass number.
39.What is the relative mass of a neutron?
Easy
- A0
- B1
- C1/1840
- D2
40.Match each description to the correct type of substance.
Medium
- Made of only one type of atom
- Two or more elements chemically combined
- Two or more substances not chemically combined
- Element
- Compound
- Mixture
41.Complete the sentence.
Easy
The atomic number is the number of ____ in the nucleus of an atom.
42.How many electrons are in a neutral atom of aluminium (atomic number 13)?
Easy
43.Name the three states of matter.
Easy
____, ____, ____
44.An atom of element X has 20 protons and 20 neutrons. What is its mass number?
Easy
45.Name the group of elements that have a full outer shell of electrons and are unreactive.
Easy
46.Complete the sentence about the structure of an atom.
Easy
The three subatomic particles are the ____, ____, and ____.
47.Complete the sentence about atomic number.
Easy
The atomic number (or proton number) is the number of ____ in the nucleus of an atom.
48.Complete the sentence about electronic configuration.
Easy
The electronic configuration of a neutral magnesium atom is ____.
49.Explain why isotopes of the same element have the same chemical properties.
Medium
50.An atom of element X has atomic number 29 and mass number 63. Determine the number of protons, neutrons, and electrons in a neutral atom of X.
Medium
51.Describe how you would use a measuring cylinder and a balance to determine the density of a small, irregularly shaped stone.
Medium
52.How many electrons are in a neutral atom of aluminium (atomic number 13)?
Easy
- A12
- B13
- C14
- D15
53.An atom of element X has 20 protons and 20 neutrons. What is its mass number?
Easy
- A40
- B48
- C44
- D36

फ्लैशकार्ड

What is an element?

A substance made of atoms that all contain the same number of protons and cannot be split into anything simpler by chemical means.

What is a compound?

A pure substance made up of two or more elements chemically combined. Compounds cannot be separated into their elements by physical means.

What is a mixture?

A combination of two or more substances (elements and/or compounds) that are not chemically combined. Mixtures can be separated by physical methods such as filtration or evaporation.

What are the three subatomic particles and their relative masses?

Proton (relative mass 1), neutron (relative mass 1), electron (relative mass 1/1840).

What are the charges of proton, neutron, and electron?

Proton: 1+, neutron: 0 (neutral), electron: 1-.

Where are protons and neutrons located in an atom?

They are located at the centre of the atom, which is called the nucleus.

What is the atomic number (proton number)?

The number of protons in the nucleus of an atom. It determines the element and its position on the Periodic Table.

What is the mass number (nucleon number)?

The total number of protons and neutrons in the nucleus of an atom.

How do you calculate the number of neutrons in an atom?

Number of neutrons = mass number – atomic number (proton number).

In a neutral atom, how do the numbers of protons and electrons compare?

In a neutral atom, the number of protons equals the number of electrons.

What is the maximum number of electrons in the first, second, and third electron shells?

First shell: 2 electrons, second shell: 8 electrons, third shell: 8 electrons (simplified model).

What is the electronic configuration of carbon (atomic number 6)?

2,4 (2 electrons in the first shell, 4 in the second shell).

What is the electronic configuration of sodium (atomic number 11)?

2,8,1 (2 in first shell, 8 in second, 1 in third).

How does the electronic configuration relate to the period of an element?

The number of occupied shells (number of notations) equals the period number.

How does the electronic configuration relate to the group of an element (Groups I-VII)?

The number of electrons in the outer shell (last notation) equals the group number.

Why are noble gases unreactive?

They have full outer shells of electrons, making them very stable.

What are isotopes?

Atoms of the same element with the same number of protons but different numbers of neutrons.

Why do isotopes of the same element have the same chemical properties?

They have the same number of electrons in their outer shells, which determines chemical behaviour.

How do isotopes differ in physical properties?

Isotopes have different masses due to different numbers of neutrons, affecting physical properties like density, boiling point, and melting point.

What is the relative atomic mass unit based on?

One relative atomic mass unit is equal to 1/12 the mass of a carbon-12 atom.

What is the valence shell?

The outermost shell of an atom, which contains the valence electrons.

What is the electronic configuration of a sodium ion (Na+)?

2,8 (sodium atom loses one electron, leaving 10 electrons).

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