The period number indicates. Group of the periodic table. Electronic structure of noble gases
A group of the periodic system of chemical elements is a sequence of atoms in increasing nuclear charge that have the same type of electronic structure. The group number is determined by the number of electrons on the outer shell of the atom (valence electrons) ... Wikipedia
The fourth period of the periodic system includes elements of the fourth row (or fourth period) of the periodic system of chemical elements. The structure of the periodic table is based on rows to illustrate repeating (periodic) ... ... Wikipedia
The first period of the periodic system includes elements of the first row (or first period) of the periodic system of chemical elements. The structure of the periodic table is based on rows to illustrate repeating (periodic) trends in... ... Wikipedia
The second period of the periodic system includes elements of the second row (or second period) of the periodic system of chemical elements. The structure of the periodic table is based on rows to illustrate repeating (periodic) trends in ... Wikipedia
The fifth period of the periodic system includes elements of the fifth row (or fifth period) of the periodic system of chemical elements. The structure of the periodic table is based on rows to illustrate repeating (periodic) trends in... ... Wikipedia
The third period of the periodic system includes elements of the third row (or third period) of the periodic system of chemical elements. The structure of the periodic table is based on rows to illustrate repeating (periodic) trends... Wikipedia
The seventh period of the periodic system includes elements of the seventh row (or seventh period) of the periodic system of chemical elements. The structure of the periodic table is based on rows to illustrate repeating (periodic) trends... Wikipedia
The sixth period of the periodic system includes elements of the sixth row (or sixth period) of the periodic system of chemical elements. The structure of the periodic table is based on rows to illustrate repeating (periodic) trends in... ... Wikipedia
The short form of the periodic table is based on the parallelism of oxidation states of elements of the main and minor subgroups: for example, the maximum oxidation state of vanadium is +5, like phosphorus and arsenic, the maximum oxidation state of chromium is +6 ... Wikipedia
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1. The period number in D.I. Mendeleev’s Periodic System corresponds to
1) the number of energy levels in an atom
2) the number of valence electrons in an atom
3) the number of unpaired electrons in an atom
4) the total number of electrons in an atom
2. The number of electrons in the electron shell of an atom is determined
1) number of protons
2) number of neutrons
3) the number of energy levels
4) the value of the relative atomic mass
3. In the series of chemical elements, silicon → phosphorus → sulfur decreases
1) the ability of an atom to accept electrons
2) highest oxidation state
3) lowest oxidation state
4) atomic radius
4. For elements of groups A, the atomic number decreases with increasing
1) atomic radius
2) charge of the atomic nucleus
3) the number of valence electrons in atoms
4) electronegativity
5. In the main subgroups of the Periodic Table of D.I. Mendeleev, from bottom to top, the main properties of metal hydroxides
1) increase
2) decrease
3) do not change
4) change periodically
6. Among the elements of group IVA, the maximum atomic radius is
1) germanium
2) carbon
3) tin
4) silicon
7. The metallic properties of the element are most pronounced
1) Na
2) Mg
3) K
4) Sa
8. The element has less pronounced non-metallic properties than silicon
1) carbon
2) germanium
3) phosphorus
4) nitrogen
9. The strongest base corresponds to the element
If you find the periodic table difficult to understand, you are not alone! Although it can be difficult to understand its principles, learning how to use it will help you when studying science. First, study the structure of the table and what information you can learn from it about each chemical element. Then you can begin to study the properties of each element. And finally, using the periodic table, you can determine the number of neutrons in an atom of a particular chemical element.
Steps
Part 1
Table structure-
As you can see, each subsequent element contains one more proton than the element preceding it. This is obvious when you look at the atomic numbers. Atomic numbers increase by one as you move from left to right. Because elements are arranged in groups, some table cells are left empty.
- For example, the first row of the table contains hydrogen, which has atomic number 1, and helium, which has atomic number 2. However, they are located on opposite edges because they belong to different groups.
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Learn about groups that contain elements with similar physical and chemical properties. The elements of each group are located in the corresponding vertical column. They are typically identified by the same color, which helps identify elements with similar physical and chemical properties and predict their behavior. All elements of a particular group have the same number of electrons in their outer shell.
- Hydrogen can be classified as both alkali metals and halogens. In some tables it is indicated in both groups.
- In most cases, the groups are numbered from 1 to 18, and the numbers are placed at the top or bottom of the table. Numbers can be specified in Roman (eg IA) or Arabic (eg 1A or 1) numerals.
- When moving along a column from top to bottom, you are said to be “browsing a group.”
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Find out why there are empty cells in the table. Elements are ordered not only according to their atomic number, but also by group (elements in the same group have similar physical and chemical properties). Thanks to this, it is easier to understand how a particular element behaves. However, as the atomic number increases, elements that fall into the corresponding group are not always found, so there are empty cells in the table.
- For example, the first 3 rows have empty cells because transition metals are only found from atomic number 21.
- Elements with atomic numbers 57 to 102 are classified as rare earth elements, and are usually placed in their own subgroup in the lower right corner of the table.
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Each row of the table represents a period. All elements of the same period have the same number of atomic orbitals in which the electrons in the atoms are located. The number of orbitals corresponds to the period number. The table contains 7 rows, that is, 7 periods.
- For example, atoms of elements of the first period have one orbital, and atoms of elements of the seventh period have 7 orbitals.
- As a rule, periods are designated by numbers from 1 to 7 on the left of the table.
- As you move along a line from left to right, you are said to be “scanning the period.”
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Learn to distinguish between metals, metalloids and non-metals. You will better understand the properties of an element if you can determine what type it is. For convenience, in most tables metals, metalloids, and nonmetals are designated by different colors. Metals are on the left and non-metals are on the right side of the table. Metalloids are located between them.
Part 2
Element designations-
Each element is designated by one or two Latin letters. As a rule, the element symbol is shown in large letters in the center of the corresponding cell. A symbol is a shortened name for an element that is the same in most languages. Element symbols are commonly used when conducting experiments and working with chemical equations, so it is helpful to remember them.
- Typically, element symbols are abbreviations of their Latin name, although for some, especially recently discovered elements, they are derived from the common name. For example, helium is represented by the symbol He, which is close to the common name in most languages. At the same time, iron is designated as Fe, which is an abbreviation of its Latin name.
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Pay attention to the full name of the element if it is given in the table. This element "name" is used in regular texts. For example, "helium" and "carbon" are names of elements. Usually, although not always, the full names of the elements are listed below their chemical symbol.
- Sometimes the table does not indicate the names of the elements and only gives their chemical symbols.
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Find the atomic number. Typically, the atomic number of an element is located at the top of the corresponding cell, in the middle or in the corner. It may also appear under the element's symbol or name. Elements have atomic numbers from 1 to 118.
- The atomic number is always an integer.
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Remember that the atomic number corresponds to the number of protons in an atom. All atoms of an element contain the same number of protons. Unlike electrons, the number of protons in the atoms of an element remains constant. Otherwise, you would get a different chemical element!
- The atomic number of an element can also determine the number of electrons and neutrons in an atom.
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Usually the number of electrons is equal to the number of protons. The exception is the case when the atom is ionized. Protons have a positive charge and electrons have a negative charge. Because atoms are usually neutral, they contain the same number of electrons and protons. However, an atom can gain or lose electrons, in which case it becomes ionized.
- Ions have an electrical charge. If an ion has more protons, it has a positive charge, in which case a plus sign is placed after the element symbol. If an ion contains more electrons, it has a negative charge, indicated by a minus sign.
- The plus and minus signs are not used if the atom is not an ion.
Consists of vertical rows (groups) and horizontal rows (periods). To better understand the principles of combining elements into groups and periods, let's consider several elements, say, the first, fourth and seventh groups.
From the above electronic configurations it is clear that the outer (highest in energy) electron shells of atoms of the same group are filled with electrons equally. Elements located in the same vertical column of the table belong to one group. Group IVA elements of the periodic table have two electrons in the s orbital and two electrons in the p orbital. The configuration of the outer electron shell of fluorine F, chlorine Cl and bromine Br atoms is also the same (two s and five p electrons). And these elements belong to one group (VIIA). Atoms of elements of the same group have the same structure of the outer electron shell. That is why such elements have similar chemical properties. The chemical properties of each element are determined by the electronic structure of the atoms of this element . This is a fundamental principle of modern chemistry. It is this that underlies the periodic table.
The group number of the periodic table corresponds to the number of electrons in the outer electron shell atoms of elements of this group. The number of the period (horizontal row of the periodic table) coincides with the number of the highest occupied electron orbital. For example, sodium and chlorine are both elements of the 3rd period and both types of atoms have the highest, electron-filled level - the third.
Strictly speaking, the number of electrons in the outer electron shell determines the group number only for the so-called non-transition elements located in groups with the letter index A.
The electronic structure of atoms determines the chemical and physical properties of elements. And since the electronic structure of atoms repeats itself after a period, the properties of the elements also repeat periodically.
The periodic law of D. I. Mendeleev has the following formulation: “the properties of chemical elements, as well as the forms and properties of the simple substances and compounds they form, periodically depend on the magnitude of the charges of the nuclei of their atoms”.
Atomic sizes
We should dwell on two more types of information obtained from the periodic table. The first of these is the question of the size (radius) of atoms. If you move down within a given group, moving to each next element means filling the next, higher and higher level with electrons. In group IA, the outer electron of the sodium atom is in the 3s orbital, potassium is in the 4s orbital, rubidium is in the 5s orbital, etc. Since the 4s orbital is larger in size than the 3s orbital, the potassium atom is larger in size than sodium atom. For the same reason in each group the sizes of atoms increase from top to bottom .
As you move to the right through a period, atomic masses increase, but the sizes of atoms, as a rule, decrease. In the 2nd period, for example, the neon Ne atom is smaller in size than the fluorine atom, which, in turn, is smaller than the oxygen atom.
Electronegativity
Another trend revealed by the periodic table is the natural change in the electronegativity of elements, that is, the relative ability of atoms to attract electrons that form bonds with other atoms. For example, noble gas atoms do not tend to gain or lose electrons, while metal atoms readily give up electrons, and non-metal atoms readily accept them. Electronegativity (the ability to attract, acquire electrons) increases from left to right within a period and from bottom to top within a group. The last group (inert gases) falls outside of these patterns.
Fluorine F, located in the upper right corner of the periodic table, is the most electronegative element, and francium Fr, located in the lower left corner, is the least electronegative. The change in electronegativity is also shown by arrows in the figure.
Using this regularity, we can, for example, argue that oxygen is a more electronegative element than carbon or sulfur. This means that oxygen atoms attract electrons more strongly than carbon and sulfur atoms.Pauling's first and widely known scale of relative atomic electronegativities ranges from 0.7 for francium atoms to 4.0 for fluorine atoms.
Electronic structure of noble gases
The elements of the last group of the periodic table are called inert (noble) gases. In the atoms of these elements, except for helium He, there are eight electrons in the outer electron shell. Noble gases do not enter into chemical reactions and do not form any compounds with other elements (except for very few exceptions). This is because the configuration of eight electrons in the outer electron shell is extremely stable.Atoms of other elements form chemical bonds in such a way that they have eight electrons in their outer shell. This position is often called octet rule
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The periodic table, or periodic table of chemical elements, begins in the upper left corner and ends at the end of the last row of the table (lower right corner). The elements in the table are arranged from left to right in increasing order of their atomic number. The atomic number shows how many protons are contained in one atom. In addition, as the atomic number increases, the atomic mass also increases. Thus, by the location of an element in the periodic table, its atomic mass can be determined.
