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3 years ago

Which statement about the elements in the periodic table is true

Chemistry

2 answers:

miss Akunina [59]3 years ago

8 0

Answer:

The reactivity of alkali metals increases as atomic mass increases.

Explanation:

There are six elements in the periodic table that can be classified as alkali metals. These elements are extremely reactive and it is correct to say that the reactivity of alkali metals increases as the atomic mass increases.

These metals can be found in the IA family of the periodic table and contain the names: Lithium, Sodium, Potassium, Rubidium, Cesium, Francium.

egoroff_w [7]3 years ago

6 0

A. The number of valence electrons increases as atomic mass increases. == Generally true for the representative elements since atomic mass generally increases with increasing Z.

B. The reactivity of alkali metals increases as atomic mass increases. == True. Atomic mass increases down the column and so does reactivity

C. The reactivity of the halogens increases as atomic mass increases. == False. Reactivity decreases down the column.

D. The number of valence electrons decreases across a period. == False. In general, the number of valence electrons increases across a period, particularly for the representative elements.

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Which element is placed in the same period as ruthenium but has a higher atomic number than it?

emmasim [6.3K]

Answer:

The part that is put in the same time as ruthenium, but has a greater number of atoms than silver.

8 0

3 years ago

How many protons , neutrons and electrons are in an atom of magnesium-24?

Minchanka [31]

Here is your answer:

Theirs 12 protons, 12 electrons, and 14 neutrons!

Reason: When you look at the atomic number for any element on the table with all of the elements that's how many protons, and electrons their are in the substance (or element) you find how many neutrons by rounding the number under the atomic number which will equal 14!

Your answer is 12:12:14

8 0

3 years ago

(a) (1)

Elis [28]

Explanation:

The ionization energy of an atom is the amount of energy that is required to remove an electron from a mole of atoms in the gas phase:

M(g) ® M+(g) + e-

It is possible to remove more electrons from most elements, so this quantity is more precisely known as the first ionization energy, the energy to go from neutral atoms to cations with a 1+ charge. The second ionization energy is the energy that is required to remove a second electron, to form 2+ cations from 1+ cations:

M+(g) ® M2+(g) + e-

The third ionization energy is the energy required to form 3+ cations:

M2+(g) ® M3+(g) + e-

and so on. Ionization energies are always positive numbers, because energy must be supplied (an endothermic energy change) to separate electrons from atoms. The second ionization energy is always larger than the first ionization energy, because it requires even more energy to remove an electron from a cation than it is from a neutral atom.

The first ionization energy varies in a predictable way across the periodic table. The ionization energy decreases from top to bottom in groups, and increases from left to right across a period. Thus, helium has the largest first ionization energy, while francium has one of the lowest.

From top to bottom in a group, orbitals corresponding to higher values of the principal quantum number (n) are being added, which are on average further away from the nucleus. Since the outermost electrons are further away, they are less strongly attracted by the nucleus, and are easier to remove, corresponding to a lower value for the first ionization energy.From left to right across a period, more protons are being added to the nucleus, but the number of electrons in the inner, lower-energy shells remains the same. The valence electrons feel a higher effective nuclear charge — the sum of the charges on the protons in the nucleus and the charges on the inner, core electrons. The valence electrons are therefore held more tightly, the atom decreases in size (see atomic radius), and it becomes increasingly difficult to remove them, corresponding to a higher value for the first ionization energy.

The following charts illustrate the general trends in the first ionization energy:

Dunno kung tama beng pero trysorry kung mali

8 0

3 years ago

Name this compound please

jasenka [17]

Answer:

Ethanol

Explanation:

2 C atoms and a single OH group.

Formula: C2H5OH

4 0

4 years ago

Need help asap!

Scilla [17]

Answer: 1. C. polar covalent: electrons shared between silicon and sulfur but attracted more to the sulfur

2. B) $NH_3$

3. B) Fluorine

Explanation:

1. A polar covalent bond is defined as the bond which is formed when there is a difference of electronegativities between the atoms.

Electronegativity difference = electronegativity of sulphur- electronegativity of silicon = 2.5 -1.8 = 0.7

Thus as electronegativity difference is less than 1.7 , the cond is polar covalent and as electronegativity of sulphur is more , the electrons will be more towards sulphur.

2. A molecular compound is usually composed of two or more nonmetal elements. Example: $NH_3$

Ionic compound is formed by the transfer of electrons from metals to non metals. Example: $Mg_3N_2$ , $AlCl_3$ and $LiBr$

3. For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.

Here K is having an oxidation state of +1 and as the compound formed is KZ, the oxidation state of non metallic element Z should be -1. Thus the element Z is flourine which exists as diatomic gas $F_2$

4 0

3 years ago