a force that does not involve physical contact between two objects ic called field force.
Answer:because of small amount of oxygen
Explanation:
If you get higher by the atmosphere the air will start to decrease
b. (1) base; (2) springing line
c. (1) keystone; (2) groin vault
d. (1) sides; (2) post-and-lintel
An arch carries the thrust of weight to its sides. With a post-and-lintel, the horizontal part of the structure supports all the weight above it. The reason is that the post and lintel is a system of construction. In this the powerful parallel components are kept up by powerful upward components that has large cavities between them.
Therefore, an arch carries the thrust of weight to its sides for balancing purposes.
D- i just took the test
3. By what property did Moseley suggest that the periodic table be arranged?
4. “The properties of the elements repeat periodically” defines the _____.
5. What is a period and how many are there in the periodic table?
6. What is a group (also called a family)? How many are there in the periodic table?
7. State the number of valence electrons in the following:
Element Valence Electrons
Magnesium
Phosphorous
Fluorine
Neon
8. Give the names and chemical symbols for the following:
Atomic Number Element Name Chemical Symbol
13
92
5
25
9. List, by number, both the period and group of each of these elements.
Element Symbol Period Group
Beryllium Be
Iron Fe
Lead Pb
10. Which of the following pairs of elements belong to the same period? Highlight
a. Na and Cl b. Na and Li c. Na and Cu d. Na and Ne
11. Which of the following pairs of elements belong to the same group? Highlight
a. H and He b. Li and Be c. C and Pb d. Ga and Ge
12. What group numbers are the transitions elements?
13. What are the group 1/IA elements called?
14. What are the group 2/IIA elements called?
15. What are the group 17/VIIA elements called?
16. What are the group 18/VIIIA elements called?
17. Which alkali metal belongs to the sixth period?
18. Which halogen belongs to the fourth period?
19. What element is in the fifth period and the eleventh group?
20. What is the heaviest noble gas?
21. What is the heaviest alkaline earth metal?
22. Would you expect strontium to be, chemically, more similar to calcium or rubidium and WHY?
23. List the three lightest noble gases.
24. List all of the alkali metals
The first published classification of the periodic table is by Dmitri Mendeleev who arranged it by atomic mass, but it was later rearranged by Henry Moseley by atomic number. This forms the basis of the modern periodic table. Various chemistry concepts related to the periodic table such as groups, periods, valence electrons, and names of certain elements are also discussed.
The first published classification of elements which forms the basis of our periodic table today was by Dmitri Mendeleev. Mendeleev initially arranged the elements by their atomic mass, and he noticed that the properties of elements repeated periodically when arranged in this order. However, later on, Henry Moseley suggested that the periodic table be arranged by atomic number (the number of protons in an atom's nucleus), which is how the modern periodic table is ordered.
"The properties of the elements repeat periodically" defines the Periodic Law. A 'period' in the periodic table is a horizontal row and there are 7 periods. A 'group' or 'family' in the periodic table is a vertical column and there are 18 groups.
Magnesium has 2 valence electrons, Phosphorous has 5, Fluorine has 7, and Neon has 8. The elements with atomic numbers 13, 92, 5, and 25 are Aluminum (Al), Uranium (U), Boron (B), and Manganese (Mn) respectively.
Beryllium (Be) belongs to period 2 and group 2, Iron (Fe) is in period 4 and group 8, and Lead (Pb) is in period 6 and group 14. The two pairs of elements that belong to the same period are Na and Cl, and Na and Ne. The pairs that belong to the same group are H and He, and Ga and Ge.
The transition elements are in groups 3-12. The group 1/IA elements are called Alkali metals, the group 2/IIA elements are called Alkaline earth metals, the group 17/VIIA elements are called Halogens, and the group 18/VIIIA elements are called Noble gases. The alkali metal that belongs to the sixth period is Cesium, the halogen that belongs to the fourth period is Bromine, the element in the fifth period and the eleventh group is Silver. The heaviest noble gas is Radon and the heaviest alkaline earth metal is Radium. Strontium is chemically more similar to Calcium, as they are in the same group and have the same number of valence electrons. The three lightest noble gases are Helium, Neon, and Argon, and the alkali metals are Lithium, Sodium, Potassium, Rubidium, Cesium, and Francium.
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Answer:
False
Explanation: