Chemistry: Structure of Atoms

In the quantum mechanical model, electrons do not move in fixed circular paths. Instead, they exist in probabilistic orbitals around the nucleus.

In a neutral atom, the number of electrons equals the number of protons, which is the atomic number. Here, the atomic number is 8, so there are 8 electrons.

filling the orbitals according to the energy level. Follow the order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p

The mass of an electron is very small compared to that of protons and neutrons, so it does not significantly contribute to the overall mass of the atom.

The d subshell has 5 orbitals, and since each orbital can hold 2 electrons, it can hold a total of 5×2=105×2=10 electrons.

The Aufbau principle states that electrons fill orbitals starting from the lowest energy level to the highest.

To find the relative atomic mass of the element with isotopes X-23 and X-24 existing in a ratio of 3:1, we can follow these steps:Step-by-Step Calculation: Isotope1 X-23 has a mass1 of 23 and exists in a ratio of 3. And Isotope2 X-24 has a mass2 of 24 and exists in a ratio2 which is 1. Calculate the weighted average:The relative atomic mass AA can be calculated using the formula: A=(mass1×ratio1)+(mass2×ratio2)/(ratio1+ratio2)=(23×3)+(24×1)/3+1=23.25

The number of neutrons can be calculated using the formula: Neutrons=Mass Number−Atomic NumberNeutrons=Mass Number−Atomic Number For this atom, it would be: 40−21=1940−21=19

The relative atomic mass of nitrogen is approximately 14.01, not 36. The other values are correct: carbon is 12, hydrogen is 1, and oxygen is 16.

The mass number can be calculated using the formula: Mass Number=Atomic Number+NeutronsMass Number=Atomic Number+Neutrons For this atom, it would be: 8+7=158+7=15

Valence electrons are the electrons in the highest energy level (outermost shell) of an atom and are involved in chemical bonding.

The L shell can hold a maximum of 8 electrons. The total number of electrons in a shell can be calculated using the formula 2n22n2, where nn is the shell number (for L, n=2n=2).

Atoms with a fully filled valence shell typically resemble noble gases and are chemically inert (non-reactive). This configuration is stable and is often referred to as the noble gas configuration.

To find the relative atomic mass of the element with isotopes X-20 and X-22 existing in a ratio of 3:1, we can use the following calculation:Step-by-Step Calculation:Identify the isotopes and their ratios: Isotope1 X-20 has a mass1 of 20 and exists in a ratio1= 3. Isotope2 X-22 has a mass2 of 22 and exists in a ratio2 of 1. Calculate the weighted average:The relative atomic mass formula: =(mass1×ratio1)+(mass2×ratio2)/(ratio1+ratio2). So if we plug the values into the formula: A=(20×3)+(22×1)/(3+1)= 22.5

An orbital is a region in an atom where there is a high probability of finding electrons

A mass spectrometer separates particles based on their mass-to-charge ratio. If an element shows two peaks in the mass spectrum, it means that there are two different masses present, which corresponds to the presence of two isotopes of that element. Isotopes are atoms of the same element that have different numbers of neutrons, resulting in different atomic masses

The d-subshell has five orbitals, which can hold a maximum of 10 electrons.

An atom is electrically neutral when it has the same number of positively charged protons in the nucleus as negatively charged electrons surrounding the nucleus. This balance results in no overall charge.

The s-subshell has one orbital, which can hold a maximum of 2 electrons.

Protons have a positive charge, while electrons carry a negative charge. This statement is incorrect.

The mass of an atom is actually estimated relative to carbon-12 (¹²C), not oxygen-16 (¹⁶O). The atomic mass unit (amu) is defined based on the mass of carbon-12, where 1 amu is a twelfth of the mass of a carbon-12 atom.

These are the three fundamental subatomic particles that make up an atom. Protons are positively charged, neutrons are neutral, and electrons are negatively charged.

one molecule of Cl is monoatomic, one molecule of oxygen (O2) is diatomic, if the element contains 3 atoms it is triatomic eg , Ozone , O3 if the molecule of the element contains 4

The mass number is the sum of the number of protons and neutrons in an atom's nucleus. It does not include electrons.

To find the relative atomic mass of the element with isotopes X-16, X-17, and X-18 existing in a ratio of 3:1:1, we can use the following calculation: Step-by-Step Calculation:Identify the isotopes and their ratios:Isotope1 X-16 has a mass1 of 16 and exists in a ratio1 which is3. Then Isotope2 X-17 has a mass2 of 17 and exists in a ratio2 which is 1. Finally Isotope3 X-18 has a mass3 of 18 and exists in a ratio3 with is 1. Calculate the weighted average:The relative atomic mass =(mass1×ratio1)+(mass2×ratio2)+(mass3×ratio3)/(ratio1+ratio2+ratio3). Plugging the values into the forula: =(16×3)+(17×1)+(18×1)/(3+1+1)=16.6

The atomic mass scale is based on the carbon-12 isotope, which is commonly used as the standard reference for atomic masses. However, if you are specifically choosing from the options provided, the most direct answer is "carbon."

Dalton's atomic theory posits that atoms are indivisible and cannot be created or destroyed in chemical reactions. This statement contradicts that principle, as atoms can only rearrange during reactions but cannot be created from other atoms.

The correct notation places the shell number before the subshell letter (e.g., 2s2s, 3p3p). The other statements are accurate in their descriptions.

Atomic Number: The atomic number of an element is defined as the number of protons in the nucleus of an atom and is always a whole number. It cannot be in fractions.

In a neutral atom, the number of electrons equals the number of protons, which is the atomic number. Here, the atomic number is 21, so there are 21 electrons.

The electron configuration for 12 electrons is 1s2, 2s2, 2p6, 3s2, meaning the last electron is in the third shell.( the first shell has 2 electrons, the second shell holds 8 electrons and the remaining 2 go into the third shell

Electrons occupy the shells (energy levels) around the nucleus of an atom. Protons and neutrons are found in the nucleus.

Protons carry a positive charge. The statement about protons being neutral is incorrect.

Dalton's atomic theory states that atoms combine in whole-number ratios to form compounds. The statement about combining in "small fractions" contradicts this principle.

they are atoms of same elements with the same atomic number (Z) but different mass number. This means they have the same number of protons but different number of neutrons in their nucleus

Isotope A: Has a mass of 10 and a relative abundance of 70% (0.70). Isotope B: Has a mass of 11 and a relative abundance of 30% (0.30). Contribution of A=Mass of A×Relative abundance of A=10×0.70=7.0. Contribution of B=Mass of B×Relative abundance of B=11×0.30=3.3. adding the two gives 10.3

The nucleus of an atom is made up of protons and neutrons. Electrons are not part of the nucleus; they orbit around it.

The atomic mass unit (amu) is defined relative to carbon-12, where one amu is one-twelfth of the mass of a carbon-12 atom. This isotope serves as the standard reference point for measuring and comparing the masses of all other atoms.

The p-subshell has three orbitals (px, py, pz), which can collectively hold a maximum of 6 electrons.

An atom is composed of a nucleus (containing protons and neutrons) and electron shells (where electrons reside). The other options do not correctly represent the structure of an atom.

The f subshell has 7 orbitals, and since each orbital can hold 2 electrons, it can hold a total of 7×2=147×2=14 electrons.

Hydrogen typically has one proton and one electron, but it usually has no neutrons in its most abundant isotope (protium). There are isotopes of hydrogen that contain neutrons (like deuterium and tritium), but the most common form of hydrogen (protium) does not have any neutrons.

The configuration is written some thing like 1s2-2s2-2p6. the first number is the shell number which is first written as whole number starting from 1 for K, 2 for L , 3 for M etc. then it is followed by the subshell which  is s, p,d or f and then the number of electrons in the subshell orbit is written last as superscript. so the 6 in 1p6 is the number of electrons

A mass spectrometer is an instrument used to measure the mass-to-charge ratio of ions. It can accurately determine the atomic mass of an atom by analyzing the isotopes present. The other options (electrometer, hydrometer, thermometer) are not used for measuring atomic mass.

Each orbital can hold a maximum of 2 electrons due to the Pauli exclusion principle.

The first electron fills the 1s orbital in the first shell.

Key Definitions:Atomic Number (Z): The number of protons in an atom, which also determines the element's identity. Mass Number (A): The total number of protons and neutrons in the nucleus of an atom. Neutrons: Calculated as the mass number minus the atomic number (A - Z). Electrons: In a neutral atom, the number of electrons equals the number of protons. Given: Mass Number (A) = 27 and Atomic Number (Z) = 17. Calculations: Number of Protons: This is equal to the atomic number..Protons = 17. Number of Neutrons: This is calculated as follows: Neutrons = Mass Number - Atomic Number = 27 - 17 = 10 Number of Electrons: In a neutral atom, the number of electrons equals the number of protons. Electrons = 17

The maximum number of electrons in a shell can be calculated using 2n raised to power 2 or n-squared. For the 4th shell (n=4n=4): 2(4-squared)=2(16)=32

The f-subshell has seven orbitals, which can hold a maximum of 14 electrons.

Neon (atomic number 10) has a complete outer shell with 8 valence electrons, which is the maximum for the outermost shell in the second period. Oxygen (8) has 6, phosphorus (15) has 5, and potassium (19) has 1 in its outermost shell.