biochemistry review Flashcards
What are living organisms composed of?
Matter.
What is matter composed of?
Chemical elements
How many elements are essential for human life?
About 25 elements are essential for human life
What are compounds?
A compound is a substance consisting of two or more different elements in a fixed ratio.
What do elements consist of?
Elements consist of unique atoms, which are made up of protons, neutrons, and electrons
What are atoms made of?
Each atom is made up of three types of particles: Neutrons,Protons and Electrons orbiting the shells.
What is atomic number?
The unique number of protons is an element’s atomic number.
Atoms of the same element always have the same number of protons( atomic number), true or false?
True
What are ions?
When an atom loses (+)or gains an electron(-), an ion is formed.
What happens when the number of neutrons in an atom changes?
Atoms will have different masses, thus creating isotopes.
How are chemical bonds formed?
An atom prefers to have a full amount of electrons in each shell (usually 2 or 8). If it doesn’t, it will interact with other atoms and share, gain, or lose electrons, resulting in attractions called chemical bonds
Why are some elements very reactive?
The chemical properties of elements, like stabiltity depend on the number of electrons. Sodium for example wants to lose one electron, if it is unable to do so, it becomes extremely unstable and thus making it reactive.
What is an ionic bond? Give an example.
Ionic bond: the transfer of an electron between atoms. Salt is an example ionic bond (sodium wants to lose an electron, chloride wants one , so they share)
What is a covalent bond? Give an example.
Covalent bond: the sharing of electrons between atoms.
ex: O2, N2, H2O
Covalent bonds are stronger than ionic bonds, true or false?
false. Ionic bonds are stronger than covalent bonds. Bond between H2, is covalent.
What is a non polar molecule?
If a bond has a balanced charge, it is a nonpolar molecule. (carbon dioxide is non polar)
What is a polar molecule?
If a bond has an unbalanced charge, it is a polar molecule.
Why is water a polar molecule?
Water is polar as it consists of unbalanced charges. There are covalent bonds and hydrogen bonds.
Why does water form hydrogen bonds?
Water is polar.
Explain hydrogen bonds.
Hydrogen bonds are technically not considered ‘bonds’ since they are very weak. They are referred to as ‘‘electrostatic attractions’’.
Why is water good as a dissolving agent and why is salt easily dissolved in water?
Water consists of electrostatic attractions, that will pull apart the chemical bonds of the solute, causing it to dissolve.
Salt is extremely polar because of chlorine pulling the electron very aggressively, and since water and salt is polar it dissolves easily. (like dissolves like)
Why is water so versatile?
Water’s versatility as a solvent results from the polarity of its molecules
How are aqueous solutions formed?
When polar or charged solute is dissolved in water molecules, it forms an aqueous solution.
Non polar molecules are hydrophilic. True or false?
False. Non polar molecules are hydrophobic and polar molecules are hydrophilic.
Differentiate a base and acid ?
Acid contains a large number of hydrogen ions. Base has either lost a large number of hydrogen ions or contains a large number of hydroxyl ions. (OH-)
What is a buffer?
Buffer minimizes changes in ph.
