The Modern Periodic Table of Elements contains 118 known elements organised systematically based on their atomic structure. By arranging elements according to their proton numbers, scientists can easily predict their chemical and physical properties.
Elements are organised by groups and periods, while valence electrons are lost or gained to form stable duplet or octet ions.
Elements are arranged from left to right and top to bottom in ascending order of their proton number.
The Modern Periodic Table of Elements contains 118 types of elements. In each element's box, information typically shown includes the proton number, symbol of element, name of element and relative atomic mass.
Groups are the 18 vertical columns. Periods are the 7 horizontal rows. The lanthanoids and actinoids are placed separately at the bottom of the table.
Moving from left to right across any period, metallic properties decrease while non-metallic properties increase, properties of oxides change from basic to acidic, and electrical conductivity of the elements decreases.
In a neutral atom, the number of protons equals the number of electrons. Electrons fill the shell closest to the nucleus first. For atoms with proton numbers 1 to 20, the first shell holds up to 2 electrons, the second shell holds up to 8 electrons, and the third shell holds up to 8 electrons.
Most atoms have an unstable electron arrangement and tend to achieve stability. A duplet electron arrangement has 2 electrons in the first shell, while an octet electron arrangement has 8 electrons in the outermost shell. Metal atoms donate electrons to form positive ions, while non-metal atoms accept electrons to form negative ions.
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What is the fundamental principle used to arrange elements in the Modern Periodic Table?
State two changes in physical or chemical properties that occur when moving from left to right across a period.
An atom of element \(X\) has 12 electrons with an electron arrangement of 2.8.2. How does this atom form an ion and what type of ion is produced?
An atom gains positive charge by taking in extra protons into the nucleus.
Protons remain unchanged inside the nucleus during chemical reactions. A positive ion is formed strictly because a neutral atom donates negatively charged electrons, leaving more protons than electrons.
All periods have the exact same properties.
Moving across a period results in continuous trends: metallic nature decreases, oxide nature turns from basic to acidic, and electrical conductivity decreases.
1 What is the definition of the proton number of an element?
2 A chlorine atom has an electron arrangement of 2.8.7. How does it achieve a stable electron arrangement?
3 Each of the vertical columns in the Modern Periodic Table of Elements is called a .
4 Positive ions are formed when the atoms of elements donate their outermost electrons.
Drag each group to its specific group name. On a phone, tap an answer first, then tap a matching box. Tap the Answer Choices area to return a selected item.
Write the correct group name next to each group.
Answer choices: Alkali metals • Alkaline earth metals • Halogens • Inert gases
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