9. practice: classification of matter\nquestion 1\nhow would you calculate the atomic mass of an atom of…

Question 1

Explanation:

Step1: Identify isotopes and abundances

Silver has two stable isotopes, Ag - 107 and Ag - 109. We need to know their relative abundances.

Step2: Use atomic - mass formula

The atomic mass ($A$) of an element is calculated as $A=\sum_{i} (m_i\times a_i)$, where $m_i$ is the mass of isotope $i$ and $a_i$ is the relative abundance of isotope $i$. For silver, if the mass of Ag - 107 is $m_{107}$ and its abundance is $a_{107}$, and the mass of Ag - 109 is $m_{109}$ and its abundance is $a_{109}$, then $A = m_{107}\times a_{107}+m_{109}\times a_{109}$. The relative abundances of Ag - 107 and Ag - 109 are approximately 51.84% and 48.16% respectively, and the masses of the isotopes are close to their mass - numbers (107 u and 109 u).

Answer:

Calculate using the formula $A = m_{107}\times a_{107}+m_{109}\times a_{109}$ with known isotope masses and abundances.

Question 2

Brief Explanations:

An atom is the smallest unit of an element that retains its chemical properties. It consists of a nucleus (protons and neutrons) and electrons. A molecule is formed when two or more atoms are chemically bonded together. Atoms can be the same (e.g., $O_2$) or different (e.g., $H_2O$).

Answer:

An atom is the basic unit of an element, while a molecule is made up of two or more atoms chemically bonded.

Question 3

Brief Explanations:

When lithium transfers an electron to fluorine, an ionic bond is formed. Lithium, after losing an electron, becomes a positively - charged ion ($Li^+$) as it has one more proton than electron. Fluorine, after gaining an electron, becomes a negatively - charged ion ($F^-$) as it has one more electron than proton.

Answer:

An ionic bond is formed. Lithium becomes a positively - charged ion ($Li^+$) and fluorine becomes a negatively - charged ion ($F^-$).